BASELINE: Update Chromium to 72.0.3626.110 and Ninja to 1.9.0

Change-Id: Ic57220b00ecc929a893c91f5cc552f5d3e99e922
Reviewed-by: Michael Brüning <michael.bruning@qt.io>

43 files changed, 599 insertions, 156 deletions

diff --git a/chromium/third_party/blink/renderer/core/html/custom/README.md b/chromium/third_party/blink/renderer/core/html/custom/README.md
index 243b82bd0b7..d8cab10145c 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/README.md
+++ b/chromium/third_party/blink/renderer/core/html/custom/README.md
@@ -83,7 +83,7 @@ with CustomElement so you can run them with:
 ###### Layout Tests
 
 The custom element layout tests are generally in
-third_party/WebKit/LayoutTests/custom-elements.
+third_party/blink/web_tests/custom-elements.
 
 All custom elements layout tests use the [web-platform-tests
 harness](https://web-platform-tests.org/) and follow its style. The
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element.cc
index 25176be6956..372e3ec5cb5 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element.cc
@@ -9,6 +9,7 @@
 #include "third_party/blink/renderer/core/frame/local_dom_window.h"
 #include "third_party/blink/renderer/core/html/custom/ce_reactions_scope.h"
 #include "third_party/blink/renderer/core/html/custom/custom_element_definition.h"
+#include "third_party/blink/renderer/core/html/custom/custom_element_form_associated_callback_reaction.h"
 #include "third_party/blink/renderer/core/html/custom/custom_element_reaction_stack.h"
 #include "third_party/blink/renderer/core/html/custom/custom_element_registry.h"
 #include "third_party/blink/renderer/core/html/custom/v0_custom_element.h"
@@ -98,7 +99,7 @@ bool CustomElement::ShouldCreateCustomElement(const AtomicString& name) {
 
 bool CustomElement::ShouldCreateCustomElement(const QualifiedName& tag_name) {
   return ShouldCreateCustomElement(tag_name.LocalName()) &&
-         tag_name.NamespaceURI() == HTMLNames::xhtmlNamespaceURI;
+         tag_name.NamespaceURI() == html_names::xhtmlNamespaceURI;
 }
 
 bool CustomElement::ShouldCreateCustomizedBuiltinElement(
@@ -110,7 +111,7 @@ bool CustomElement::ShouldCreateCustomizedBuiltinElement(
 bool CustomElement::ShouldCreateCustomizedBuiltinElement(
     const QualifiedName& tag_name) {
   return ShouldCreateCustomizedBuiltinElement(tag_name.LocalName()) &&
-         tag_name.NamespaceURI() == HTMLNames::xhtmlNamespaceURI;
+         tag_name.NamespaceURI() == html_names::xhtmlNamespaceURI;
 }
 
 static CustomElementDefinition* DefinitionFor(
@@ -175,7 +176,7 @@ Element* CustomElement::CreateUncustomizedOrUndefinedElementTemplate(
   // custom element state to "undefined".
   if (level == kQNameIsValid)
     element->SetCustomElementState(CustomElementState::kUndefined);
-  else if (tag_name.NamespaceURI() == HTMLNames::xhtmlNamespaceURI &&
+  else if (tag_name.NamespaceURI() == html_names::xhtmlNamespaceURI &&
            (CustomElement::IsValidName(tag_name.LocalName()) ||
             !is_value.IsNull()))
     element->SetCustomElementState(CustomElementState::kUndefined);
@@ -261,6 +262,17 @@ void CustomElement::EnqueueAttributeChangedCallback(
                                                 new_value);
 }
 
+void CustomElement::EnqueueFormAssociatedCallback(
+    Element& element,
+    HTMLFormElement* nullable_form) {
+  auto* definition = DefinitionForElementWithoutCheck(element);
+  if (definition->HasFormAssociatedCallback()) {
+    Enqueue(&element,
+            MakeGarbageCollected<CustomElementFormAssociatedCallbackReaction>(
+                definition, nullable_form));
+  }
+}
+
 void CustomElement::TryToUpgrade(Element* element,
                                  bool upgrade_invisible_elements) {
   // Try to upgrade an element
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element.h b/chromium/third_party/blink/renderer/core/html/custom/custom_element.h
index a0eb6747e54..a7ce7c32af7 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element.h
@@ -18,6 +18,7 @@ namespace blink {
 class Document;
 class Element;
 class HTMLElement;
+class HTMLFormElement;
 class QualifiedName;
 class CustomElementDefinition;
 class CustomElementReaction;
@@ -103,6 +104,8 @@ class CORE_EXPORT CustomElement {
                                               const QualifiedName&,
                                               const AtomicString& old_value,
                                               const AtomicString& new_value);
+  static void EnqueueFormAssociatedCallback(Element& element,
+                                            HTMLFormElement* nullable_form);
 
   static void TryToUpgrade(Element*, bool upgrade_invisible_elements = false);
 
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_definition.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element_definition.cc
index 2764e2efd42..30979be3de3 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_definition.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_definition.cc
@@ -17,6 +17,7 @@
 #include "third_party/blink/renderer/core/html/custom/custom_element_reaction.h"
 #include "third_party/blink/renderer/core/html/custom/custom_element_reaction_stack.h"
 #include "third_party/blink/renderer/core/html/custom/custom_element_upgrade_reaction.h"
+#include "third_party/blink/renderer/core/html/custom/element_internals.h"
 #include "third_party/blink/renderer/core/html/html_element.h"
 #include "third_party/blink/renderer/core/html_element_factory.h"
 #include "third_party/blink/renderer/platform/bindings/exception_state.h"
@@ -29,11 +30,16 @@ CustomElementDefinition::CustomElementDefinition(
 
 CustomElementDefinition::CustomElementDefinition(
     const CustomElementDescriptor& descriptor,
-    const HashSet<AtomicString>& observed_attributes)
+    const HashSet<AtomicString>& observed_attributes,
+    const Vector<String>& disabled_features,
+    FormAssociationFlag form_association_flag)
     : descriptor_(descriptor),
       observed_attributes_(observed_attributes),
       has_style_attribute_changed_callback_(
-          observed_attributes.Contains(HTMLNames::styleAttr.LocalName())) {}
+          observed_attributes.Contains(html_names::kStyleAttr.LocalName())),
+      disable_internals_(disabled_features.Contains(String("internals"))),
+      is_form_associated_(form_association_flag == FormAssociationFlag::kYes) {}
+
 CustomElementDefinition::~CustomElementDefinition() = default;
 
 void CustomElementDefinition::Trace(blink::Visitor* visitor) {
@@ -61,7 +67,7 @@ static String ErrorMessageForConstructorResult(Element* element,
     return "The result must be in the same document";
   // 6.1.8. If result's namespace is not the HTML namespace, then throw a
   // NotSupportedError.
-  if (element->namespaceURI() != HTMLNames::xhtmlNamespaceURI)
+  if (element->namespaceURI() != html_names::xhtmlNamespaceURI)
     return "The result must have HTML namespace";
   // 6.1.9. If result's local name is not equal to localName, then throw a
   // NotSupportedError.
@@ -104,7 +110,7 @@ HTMLElement* CustomElementDefinition::CreateElementForConstructor(
   } else {
     element =
         HTMLElement::Create(QualifiedName(g_null_atom, Descriptor().LocalName(),
-                                          HTMLNames::xhtmlNamespaceURI),
+                                          html_names::xhtmlNamespaceURI),
                             document);
   }
   // TODO(davaajav): write this as one call to setCustomElementState instead of
@@ -206,6 +212,9 @@ void CustomElementDefinition::Upgrade(Element* element) {
   }
 
   element->SetCustomElementDefinition(this);
+
+  if (IsFormAssociated())
+    ToHTMLElement(element)->EnsureElementInternals().DidUpgrade();
   AddDefaultStylesTo(*element);
 }
 
@@ -230,9 +239,9 @@ void CustomElementDefinition::AddDefaultStylesTo(Element& element) {
     for (CSSStyleSheet* sheet : default_styles)
       sheet->AddToCustomElementTagNames(local_tag_name);
   }
-  element.SetNeedsStyleRecalc(kLocalStyleChange,
-                              StyleChangeReasonForTracing::Create(
-                                  StyleChangeReason::kActiveStylesheetsUpdate));
+  element.SetNeedsStyleRecalc(
+      kLocalStyleChange, StyleChangeReasonForTracing::Create(
+                             style_change_reason::kActiveStylesheetsUpdate));
 }
 
 bool CustomElementDefinition::HasAttributeChangedCallback(
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_definition.h b/chromium/third_party/blink/renderer/core/html/custom/custom_element_definition.h
index 760c9b76ce2..f94bf3ae33b 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_definition.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_definition.h
@@ -23,8 +23,14 @@ class Document;
 class Element;
 class ExceptionState;
 class HTMLElement;
+class HTMLFormElement;
 class QualifiedName;
 
+enum class FormAssociationFlag {
+  kNo,
+  kYes,
+};
+
 class CORE_EXPORT CustomElementDefinition
     : public GarbageCollectedFinalized<CustomElementDefinition>,
       public NameClient {
@@ -68,6 +74,8 @@ class CORE_EXPORT CustomElementDefinition
   virtual bool HasAdoptedCallback() const = 0;
   bool HasAttributeChangedCallback(const QualifiedName&) const;
   bool HasStyleAttributeChangedCallback() const;
+  virtual bool HasFormAssociatedCallback() const = 0;
+  virtual bool HasDisabledStateChangedCallback() const = 0;
 
   virtual void RunConnectedCallback(Element*) = 0;
   virtual void RunDisconnectedCallback(Element*) = 0;
@@ -78,6 +86,10 @@ class CORE_EXPORT CustomElementDefinition
                                            const QualifiedName&,
                                            const AtomicString& old_value,
                                            const AtomicString& new_value) = 0;
+  virtual void RunFormAssociatedCallback(Element* element,
+                                         HTMLFormElement* nullable_form) = 0;
+  virtual void RunDisabledStateChangedCallback(Element* element,
+                                               bool is_disabled) = 0;
 
   void EnqueueUpgradeReaction(Element*,
                               bool upgrade_invisible_elements = false);
@@ -103,6 +115,8 @@ class CORE_EXPORT CustomElementDefinition
   bool HasDefaultStyleSheets() const {
     return !default_style_sheets_.IsEmpty();
   }
+  bool DisableInternals() const { return disable_internals_; }
+  bool IsFormAssociated() const { return is_form_associated_; }
 
   class CORE_EXPORT ConstructionStackScope final {
     STACK_ALLOCATED();
@@ -122,7 +136,9 @@ class CORE_EXPORT CustomElementDefinition
   CustomElementDefinition(const CustomElementDescriptor&);
 
   CustomElementDefinition(const CustomElementDescriptor&,
-                          const HashSet<AtomicString>& observed_attributes);
+                          const HashSet<AtomicString>& observed_attributes,
+                          const Vector<String>& disabled_features,
+                          FormAssociationFlag form_association_flag);
 
   void AddDefaultStylesTo(Element&);
 
@@ -139,6 +155,8 @@ class CORE_EXPORT CustomElementDefinition
   HashSet<AtomicString> observed_attributes_;
   bool has_style_attribute_changed_callback_;
   bool added_default_style_sheet_ = false;
+  bool disable_internals_ = false;
+  bool is_form_associated_ = false;
 
   HeapVector<Member<CSSStyleSheet>> default_style_sheets_;
 
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_definition_test.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element_definition_test.cc
index b9377f13020..07d98d1445b 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_definition_test.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_definition_test.cc
@@ -34,9 +34,12 @@ TEST(CustomElementDefinitionTest, upgrade_clearsReactionQueueOnFailure) {
       << "sanity check: this element should be ready to upgrade";
   {
     CEReactionsScope reactions;
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Unreached>(
+        "upgrade failure should clear the reaction queue"));
     reactions.EnqueueToCurrentQueue(
-        element, new TestReaction({new Unreached(
-                     "upgrade failure should clear the reaction queue")}));
+        element, MakeGarbageCollected<TestReaction>(commands));
     ConstructorFails definition(CustomElementDescriptor("a-a", "a-a"));
     definition.Upgrade(element);
   }
@@ -50,9 +53,12 @@ TEST(CustomElementDefinitionTest,
   EXPECT_EQ(CustomElementState::kUndefined, element->GetCustomElementState())
       << "sanity check: this element should be ready to upgrade";
   ResetCustomElementReactionStackForTest reset_reaction_stack;
+  HeapVector<Member<Command>>* commands =
+      MakeGarbageCollected<HeapVector<Member<Command>>>();
+  commands->push_back(MakeGarbageCollected<Unreached>(
+      "upgrade failure should clear the reaction queue"));
   reset_reaction_stack.Stack().EnqueueToBackupQueue(
-      element, new TestReaction({new Unreached(
-                   "upgrade failure should clear the reaction queue")}));
+      element, MakeGarbageCollected<TestReaction>(commands));
   ConstructorFails definition(CustomElementDescriptor("a-a", "a-a"));
   definition.Upgrade(element);
   EXPECT_EQ(CustomElementState::kFailed, element->GetCustomElementState())
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_descriptor.h b/chromium/third_party/blink/renderer/core/html/custom/custom_element_descriptor.h
index d47ce6da73e..d24e368a0b9 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_descriptor.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_descriptor.h
@@ -49,7 +49,7 @@ class CORE_EXPORT CustomElementDescriptor final {
   bool Matches(const Element& element) const {
     return LocalName() == element.localName() &&
            (IsAutonomous() || GetName() == element.IsValue()) &&
-           element.namespaceURI() == HTMLNames::xhtmlNamespaceURI;
+           element.namespaceURI() == html_names::xhtmlNamespaceURI;
   }
 
   bool IsAutonomous() const { return name_ == local_name_; }
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_form_associated_callback_reaction.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element_form_associated_callback_reaction.cc
new file mode 100644
index 00000000000..dc77d5c9cdf
--- /dev/null
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_form_associated_callback_reaction.cc
@@ -0,0 +1,30 @@
+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "third_party/blink/renderer/core/html/custom/custom_element_form_associated_callback_reaction.h"
+
+#include "third_party/blink/renderer/core/dom/document.h"
+#include "third_party/blink/renderer/core/html/custom/custom_element_definition.h"
+#include "third_party/blink/renderer/core/html/forms/html_form_element.h"
+
+namespace blink {
+
+CustomElementFormAssociatedCallbackReaction::
+    CustomElementFormAssociatedCallbackReaction(
+        CustomElementDefinition* definition,
+        HTMLFormElement* nullable_form)
+    : CustomElementReaction(definition), form_(nullable_form) {
+  DCHECK(definition->HasFormAssociatedCallback());
+}
+
+void CustomElementFormAssociatedCallbackReaction::Trace(Visitor* visitor) {
+  visitor->Trace(form_);
+  CustomElementReaction::Trace(visitor);
+}
+
+void CustomElementFormAssociatedCallbackReaction::Invoke(Element* element) {
+  definition_->RunFormAssociatedCallback(element, form_.Get());
+}
+
+}  // namespace blink
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_form_associated_callback_reaction.h b/chromium/third_party/blink/renderer/core/html/custom/custom_element_form_associated_callback_reaction.h
new file mode 100644
index 00000000000..01d1d1b2de3
--- /dev/null
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_form_associated_callback_reaction.h
@@ -0,0 +1,32 @@
+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_HTML_CUSTOM_CUSTOM_ELEMENT_FORM_ASSOCIATED_CALLBACK_REACTION_H_
+#define THIRD_PARTY_BLINK_RENDERER_CORE_HTML_CUSTOM_CUSTOM_ELEMENT_FORM_ASSOCIATED_CALLBACK_REACTION_H_
+
+#include "base/macros.h"
+#include "third_party/blink/renderer/core/html/custom/custom_element_reaction.h"
+
+namespace blink {
+
+class HTMLFormElement;
+
+class CustomElementFormAssociatedCallbackReaction final
+    : public CustomElementReaction {
+ public:
+  CustomElementFormAssociatedCallbackReaction(CustomElementDefinition*,
+                                              HTMLFormElement* nullable_form);
+  void Trace(Visitor*) override;
+
+ private:
+  void Invoke(Element*) override;
+
+  Member<HTMLFormElement> form_;
+
+  DISALLOW_COPY_AND_ASSIGN(CustomElementFormAssociatedCallbackReaction);
+};
+
+}  // namespace blink
+
+#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_HTML_CUSTOM_CUSTOM_ELEMENT_FORM_ASSOCIATED_CALLBACK_REACTION_H_
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_queue_test.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_queue_test.cc
index af1de9ce0da..651efd1e45e 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_queue_test.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_queue_test.cc
@@ -17,7 +17,10 @@ namespace blink {
 TEST(CustomElementReactionQueueTest, invokeReactions_one) {
   std::vector<char> log;
   CustomElementReactionQueue* queue = new CustomElementReactionQueue();
-  queue->Add(new TestReaction({new Log('a', log)}));
+  HeapVector<Member<Command>>* commands =
+      MakeGarbageCollected<HeapVector<Member<Command>>>();
+  commands->push_back(MakeGarbageCollected<Log>('a', log));
+  queue->Add(MakeGarbageCollected<TestReaction>(commands));
   queue->InvokeReactions(nullptr);
   EXPECT_EQ(log, std::vector<char>({'a'}))
       << "the reaction should have been invoked";
@@ -26,9 +29,24 @@ TEST(CustomElementReactionQueueTest, invokeReactions_one) {
 TEST(CustomElementReactionQueueTest, invokeReactions_many) {
   std::vector<char> log;
   CustomElementReactionQueue* queue = new CustomElementReactionQueue();
-  queue->Add(new TestReaction({new Log('a', log)}));
-  queue->Add(new TestReaction({new Log('b', log)}));
-  queue->Add(new TestReaction({new Log('c', log)}));
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('a', log));
+    queue->Add(MakeGarbageCollected<TestReaction>(commands));
+  }
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('b', log));
+    queue->Add(MakeGarbageCollected<TestReaction>(commands));
+  }
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('c', log));
+    queue->Add(MakeGarbageCollected<TestReaction>(commands));
+  }
   queue->InvokeReactions(nullptr);
   EXPECT_EQ(log, std::vector<char>({'a', 'b', 'c'}))
       << "the reaction should have been invoked";
@@ -38,16 +56,27 @@ TEST(CustomElementReactionQueueTest, invokeReactions_recursive) {
   std::vector<char> log;
   CustomElementReactionQueue* queue = new CustomElementReactionQueue();
 
-  CustomElementReaction* third = new TestReaction(
-      {new Log('c', log), new Recurse(queue)});  // "Empty" recursion
+  HeapVector<Member<Command>>* third_commands =
+      MakeGarbageCollected<HeapVector<Member<Command>>>();
+  third_commands->push_back(MakeGarbageCollected<Log>('c', log));
+  third_commands->push_back(MakeGarbageCollected<Recurse>(queue));
+  CustomElementReaction* third =
+      MakeGarbageCollected<TestReaction>(third_commands);  // "Empty" recursion
 
-  CustomElementReaction* second = new TestReaction(
-      {new Log('b', log),
-       new Enqueue(queue, third)});  // Unwinds one level of recursion
+  HeapVector<Member<Command>>* second_commands =
+      MakeGarbageCollected<HeapVector<Member<Command>>>();
+  second_commands->push_back(MakeGarbageCollected<Log>('b', log));
+  second_commands->push_back(MakeGarbageCollected<Enqueue>(queue, third));
+  CustomElementReaction* second = MakeGarbageCollected<TestReaction>(
+      second_commands);  // Unwinds one level of recursion
 
-  CustomElementReaction* first =
-      new TestReaction({new Log('a', log), new Enqueue(queue, second),
-                        new Recurse(queue)});  // Non-empty recursion
+  HeapVector<Member<Command>>* first_commands =
+      MakeGarbageCollected<HeapVector<Member<Command>>>();
+  first_commands->push_back(MakeGarbageCollected<Log>('a', log));
+  first_commands->push_back(MakeGarbageCollected<Enqueue>(queue, second));
+  first_commands->push_back(MakeGarbageCollected<Recurse>(queue));
+  CustomElementReaction* first = MakeGarbageCollected<TestReaction>(
+      first_commands);  // Non-empty recursion
 
   queue->Add(first);
   queue->InvokeReactions(nullptr);
@@ -59,11 +88,26 @@ TEST(CustomElementReactionQueueTest, clear_duringInvoke) {
   std::vector<char> log;
   CustomElementReactionQueue* queue = new CustomElementReactionQueue();
 
-  queue->Add(new TestReaction({new Log('a', log)}));
-  queue->Add(new TestReaction({new Call(WTF::Bind(
-      [](CustomElementReactionQueue* queue, Element*) { queue->Clear(); },
-      WrapPersistent(queue)))}));
-  queue->Add(new TestReaction({new Log('b', log)}));
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('a', log));
+    queue->Add(MakeGarbageCollected<TestReaction>(commands));
+  }
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(new Call(WTF::Bind(
+        [](CustomElementReactionQueue* queue, Element*) { queue->Clear(); },
+        WrapPersistent(queue))));
+    queue->Add(MakeGarbageCollected<TestReaction>(commands));
+  }
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('b', log));
+    queue->Add(MakeGarbageCollected<TestReaction>(commands));
+  }
 
   queue->InvokeReactions(nullptr);
   EXPECT_EQ(log, std::vector<char>({'a'}))
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_stack.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_stack.cc
index 17f2895c4e0..48b65d63226 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_stack.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_stack.cc
@@ -66,7 +66,7 @@ void CustomElementReactionStack::Enqueue(Member<ElementQueue>& queue,
                                          Element* element,
                                          CustomElementReaction* reaction) {
   if (!queue)
-    queue = new ElementQueue();
+    queue = MakeGarbageCollected<ElementQueue>();
   queue->push_back(element);
 
   CustomElementReactionQueue* reactions = map_.at(element);
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_stack_test.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_stack_test.cc
index 5ed8fbfa8b8..49ec44d502d 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_stack_test.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_stack_test.cc
@@ -21,8 +21,11 @@ TEST(CustomElementReactionStackTest, one) {
 
   CustomElementReactionStack* stack = new CustomElementReactionStack();
   stack->Push();
+  HeapVector<Member<Command>>* commands =
+      MakeGarbageCollected<HeapVector<Member<Command>>>();
+  commands->push_back(MakeGarbageCollected<Log>('a', log));
   stack->EnqueueToCurrentQueue(CreateElement("a"),
-                               new TestReaction({new Log('a', log)}));
+                               MakeGarbageCollected<TestReaction>(commands));
   stack->PopInvokingReactions();
 
   EXPECT_EQ(log, std::vector<char>({'a'}))
@@ -34,10 +37,20 @@ TEST(CustomElementReactionStackTest, multipleElements) {
 
   CustomElementReactionStack* stack = new CustomElementReactionStack();
   stack->Push();
-  stack->EnqueueToCurrentQueue(CreateElement("a"),
-                               new TestReaction({new Log('a', log)}));
-  stack->EnqueueToCurrentQueue(CreateElement("a"),
-                               new TestReaction({new Log('b', log)}));
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('a', log));
+    stack->EnqueueToCurrentQueue(CreateElement("a"),
+                                 MakeGarbageCollected<TestReaction>(commands));
+  }
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('b', log));
+    stack->EnqueueToCurrentQueue(CreateElement("a"),
+                                 MakeGarbageCollected<TestReaction>(commands));
+  }
   stack->PopInvokingReactions();
 
   EXPECT_EQ(log, std::vector<char>({'a', 'b'}))
@@ -49,8 +62,11 @@ TEST(CustomElementReactionStackTest, popTopEmpty) {
 
   CustomElementReactionStack* stack = new CustomElementReactionStack();
   stack->Push();
+  HeapVector<Member<Command>>* commands =
+      MakeGarbageCollected<HeapVector<Member<Command>>>();
+  commands->push_back(MakeGarbageCollected<Log>('a', log));
   stack->EnqueueToCurrentQueue(CreateElement("a"),
-                               new TestReaction({new Log('a', log)}));
+                               MakeGarbageCollected<TestReaction>(commands));
   stack->Push();
   stack->PopInvokingReactions();
 
@@ -63,11 +79,21 @@ TEST(CustomElementReactionStackTest, popTop) {
 
   CustomElementReactionStack* stack = new CustomElementReactionStack();
   stack->Push();
-  stack->EnqueueToCurrentQueue(CreateElement("a"),
-                               new TestReaction({new Log('a', log)}));
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('a', log));
+    stack->EnqueueToCurrentQueue(CreateElement("a"),
+                                 MakeGarbageCollected<TestReaction>(commands));
+  }
   stack->Push();
-  stack->EnqueueToCurrentQueue(CreateElement("a"),
-                               new TestReaction({new Log('b', log)}));
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('b', log));
+    stack->EnqueueToCurrentQueue(CreateElement("a"),
+                                 MakeGarbageCollected<TestReaction>(commands));
+  }
   stack->PopInvokingReactions();
 
   EXPECT_EQ(log, std::vector<char>({'b'}))
@@ -81,10 +107,27 @@ TEST(CustomElementReactionStackTest, requeueingDoesNotReorderElements) {
 
   CustomElementReactionStack* stack = new CustomElementReactionStack();
   stack->Push();
-  stack->EnqueueToCurrentQueue(element, new TestReaction({new Log('a', log)}));
-  stack->EnqueueToCurrentQueue(CreateElement("a"),
-                               new TestReaction({new Log('z', log)}));
-  stack->EnqueueToCurrentQueue(element, new TestReaction({new Log('b', log)}));
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('a', log));
+    stack->EnqueueToCurrentQueue(element,
+                                 MakeGarbageCollected<TestReaction>(commands));
+  }
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('z', log));
+    stack->EnqueueToCurrentQueue(CreateElement("a"),
+                                 MakeGarbageCollected<TestReaction>(commands));
+  }
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('b', log));
+    stack->EnqueueToCurrentQueue(element,
+                                 MakeGarbageCollected<TestReaction>(commands));
+  }
   stack->PopInvokingReactions();
 
   EXPECT_EQ(log, std::vector<char>({'a', 'b', 'z'}))
@@ -98,13 +141,35 @@ TEST(CustomElementReactionStackTest, oneReactionQueuePerElement) {
 
   CustomElementReactionStack* stack = new CustomElementReactionStack();
   stack->Push();
-  stack->EnqueueToCurrentQueue(element, new TestReaction({new Log('a', log)}));
-  stack->EnqueueToCurrentQueue(CreateElement("a"),
-                               new TestReaction({new Log('z', log)}));
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('a', log));
+    stack->EnqueueToCurrentQueue(element,
+                                 MakeGarbageCollected<TestReaction>(commands));
+  }
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('z', log));
+    stack->EnqueueToCurrentQueue(CreateElement("a"),
+                                 MakeGarbageCollected<TestReaction>(commands));
+  }
   stack->Push();
-  stack->EnqueueToCurrentQueue(CreateElement("a"),
-                               new TestReaction({new Log('y', log)}));
-  stack->EnqueueToCurrentQueue(element, new TestReaction({new Log('b', log)}));
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('y', log));
+    stack->EnqueueToCurrentQueue(CreateElement("a"),
+                                 MakeGarbageCollected<TestReaction>(commands));
+  }
+  {
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<Log>('b', log));
+    stack->EnqueueToCurrentQueue(element,
+                                 MakeGarbageCollected<TestReaction>(commands));
+  }
   stack->PopInvokingReactions();
 
   EXPECT_EQ(log, std::vector<char>({'y', 'a', 'b'}))
@@ -147,9 +212,17 @@ TEST(CustomElementReactionStackTest, enqueueFromReaction) {
 
   CustomElementReactionStack* stack = new CustomElementReactionStack();
   stack->Push();
-  stack->EnqueueToCurrentQueue(
-      element, new TestReaction({new EnqueueToStack(
-                   stack, element, new TestReaction({new Log('a', log)}))}));
+  {
+    HeapVector<Member<Command>>* subcommands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    subcommands->push_back(MakeGarbageCollected<Log>('a', log));
+    HeapVector<Member<Command>>* commands =
+        MakeGarbageCollected<HeapVector<Member<Command>>>();
+    commands->push_back(MakeGarbageCollected<EnqueueToStack>(
+        stack, element, MakeGarbageCollected<TestReaction>(subcommands)));
+    stack->EnqueueToCurrentQueue(element,
+                                 MakeGarbageCollected<TestReaction>(commands));
+  }
   stack->PopInvokingReactions();
 
   EXPECT_EQ(log, std::vector<char>({'a'})) << "enqueued reaction from another "
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_test_helpers.h b/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_test_helpers.h
index 29cbabc7ed8..396d89d636c 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_test_helpers.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_reaction_test_helpers.h
@@ -107,25 +107,20 @@ class Enqueue : public Command {
 
 class TestReaction : public CustomElementReaction {
  public:
-  TestReaction(std::initializer_list<Command*> commands)
-      : CustomElementReaction(nullptr) {
-    // TODO(dominicc): Simply pass the initializer list when
-    // HeapVector supports initializer lists like Vector.
-    for (auto* const command : commands)
-      commands_.push_back(command);
-  }
+  TestReaction(HeapVector<Member<Command>>* commands)
+      : CustomElementReaction(nullptr), commands_(commands) {}
   ~TestReaction() override = default;
   void Trace(blink::Visitor* visitor) override {
     CustomElementReaction::Trace(visitor);
     visitor->Trace(commands_);
   }
   void Invoke(Element* element) override {
-    for (auto& command : commands_)
+    for (auto& command : *commands_)
       command->Run(element);
   }
 
  private:
-  HeapVector<Member<Command>> commands_;
+  Member<HeapVector<Member<Command>>> commands_;
 
   DISALLOW_COPY_AND_ASSIGN(TestReaction);
 };
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry.cc
index c4ca5d9e54c..866bdc2f28f 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry.cc
@@ -89,8 +89,8 @@ CustomElementRegistry* CustomElementRegistry::Create(
 CustomElementRegistry::CustomElementRegistry(const LocalDOMWindow* owner)
     : element_definition_is_running_(false),
       owner_(owner),
-      v0_(new V0RegistrySet()),
-      upgrade_candidates_(new UpgradeCandidateMap()),
+      v0_(MakeGarbageCollected<V0RegistrySet>()),
+      upgrade_candidates_(MakeGarbageCollected<UpgradeCandidateMap>()),
       reaction_stack_(&CustomElementReactionStack::Current()) {}
 
 void CustomElementRegistry::Trace(blink::Visitor* visitor) {
@@ -107,7 +107,7 @@ CustomElementDefinition* CustomElementRegistry::define(
     ScriptState* script_state,
     const AtomicString& name,
     V8CustomElementConstructor* constructor,
-    const ElementDefinitionOptions& options,
+    const ElementDefinitionOptions* options,
     ExceptionState& exception_state) {
   ScriptCustomElementDefinitionBuilder builder(script_state, this, constructor,
                                                exception_state);
@@ -119,7 +119,7 @@ CustomElementDefinition* CustomElementRegistry::DefineInternal(
     ScriptState* script_state,
     const AtomicString& name,
     CustomElementDefinitionBuilder& builder,
-    const ElementDefinitionOptions& options,
+    const ElementDefinitionOptions* options,
     ExceptionState& exception_state) {
   TRACE_EVENT1("blink", "CustomElementRegistry::define", "name", name.Utf8());
   if (!builder.CheckConstructorIntrinsics())
@@ -150,10 +150,10 @@ CustomElementDefinition* CustomElementRegistry::DefineInternal(
 
   // Step 7. customized built-in elements definition
   // element interface extends option checks
-  if (options.hasExtends()) {
+  if (options->hasExtends()) {
     // 7.1. If element interface is valid custom element name, throw exception
-    const AtomicString& extends = AtomicString(options.extends());
-    if (ThrowIfValidName(AtomicString(options.extends()), exception_state))
+    const AtomicString& extends = AtomicString(options->extends());
+    if (ThrowIfValidName(AtomicString(options->extends()), exception_state))
       return nullptr;
     // 7.2. If element interface is undefined element, throw exception
     if (htmlElementTypeForTag(extends) ==
@@ -212,9 +212,8 @@ CustomElementDefinition* CustomElementRegistry::DefineInternal(
   CHECK(!exception_state.HadException());
   CHECK(definition->Descriptor() == descriptor);
   if (RuntimeEnabledFeatures::CustomElementDefaultStyleEnabled() &&
-      options.hasStyles())
-    definition->SetDefaultStyleSheets(options.styles());
-
+      options->hasStyles())
+    definition->SetDefaultStyleSheets(options->styles());
   definitions_.emplace_back(definition);
   NameIdMap::AddResult result = name_id_map_.insert(descriptor.GetName(), id);
   CHECK(result.is_new_entry);
@@ -304,7 +303,8 @@ void CustomElementRegistry::AddCandidate(Element* candidate) {
   if (it != upgrade_candidates_->end()) {
     set = it->value;
   } else {
-    set = upgrade_candidates_->insert(name, new UpgradeCandidateSet())
+    set = upgrade_candidates_
+              ->insert(name, MakeGarbageCollected<UpgradeCandidateSet>())
               .stored_value->value;
   }
   set->insert(candidate);
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry.h b/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry.h
index a323e28be66..5b3f44845d1 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry.h
@@ -42,7 +42,7 @@ class CORE_EXPORT CustomElementRegistry final : public ScriptWrappable {
   CustomElementDefinition* define(ScriptState*,
                                   const AtomicString& name,
                                   V8CustomElementConstructor* constructor,
-                                  const ElementDefinitionOptions&,
+                                  const ElementDefinitionOptions*,
                                   ExceptionState&);
 
   ScriptValue get(const AtomicString& name);
@@ -72,7 +72,7 @@ class CORE_EXPORT CustomElementRegistry final : public ScriptWrappable {
   CustomElementDefinition* DefineInternal(ScriptState*,
                                           const AtomicString& name,
                                           CustomElementDefinitionBuilder&,
-                                          const ElementDefinitionOptions&,
+                                          const ElementDefinitionOptions*,
                                           ExceptionState&);
 
   bool V0NameIsDefined(const AtomicString& name);
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry.idl b/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry.idl
index aab5cdf98ab..8061cb734e4 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry.idl
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry.idl
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// https://html.spec.whatwg.org/C/custom-elements.html#customelementregistry
+
 interface CustomElementRegistry {
     [CallWith=ScriptState, CEReactions, CustomElementCallbacks, RaisesException, MeasureAs=CustomElementRegistryDefine] void define(DOMString name, CustomElementConstructor constructor, optional ElementDefinitionOptions options);
     any get(DOMString name);
@@ -10,3 +12,10 @@ interface CustomElementRegistry {
 };
 
 callback CustomElementConstructor = any ();
+
+// Blink specific types. HTML standard does not explicitly define these types.
+callback CustomElementAdoptedCallback = void (Document oldOwner, Document newOwner);
+callback CustomElementAttributeChangedCallback = void (DOMString localName, DOMString? oldValue, DOMString? newValue, USVString? attrNamespace);
+callback CustomElementFormAssociatedCallback = void (HTMLFormElement? form);
+callback CustomElementDisabledStateChangedCallback = void (boolean disabled);
+
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry_test.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry_test.cc
index 7cef1b7046a..522e8116366 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry_test.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_registry_test.cc
@@ -43,7 +43,7 @@ class CustomElementRegistryTest : public PageTestBase {
 
   CustomElementDefinition* Define(const AtomicString& name,
                                   CustomElementDefinitionBuilder& builder,
-                                  const ElementDefinitionOptions& options,
+                                  const ElementDefinitionOptions* options,
                                   ExceptionState& exception_state) {
     return Registry().DefineInternal(GetScriptState(), name, builder, options,
                                      exception_state);
@@ -170,8 +170,9 @@ class LogUpgradeDefinition : public TestCustomElementDefinition {
       : TestCustomElementDefinition(
             descriptor,
             {
-                "attr1", "attr2", HTMLNames::contenteditableAttr.LocalName(),
-            }) {}
+                "attr1", "attr2", html_names::kContenteditableAttr.LocalName(),
+            },
+            {}) {}
 
   void Trace(blink::Visitor* visitor) override {
     TestCustomElementDefinition::Trace(visitor);
@@ -242,7 +243,7 @@ class LogUpgradeDefinition : public TestCustomElementDefinition {
                           Document* new_owner) override {
     logs_.push_back(kAdoptedCallback);
     EXPECT_EQ(element, element_);
-    adopted_.push_back(new Adopted(old_owner, new_owner));
+    adopted_.push_back(MakeGarbageCollected<Adopted>(old_owner, new_owner));
   }
 
   void RunAttributeChangedCallback(Element* element,
@@ -265,7 +266,7 @@ class LogUpgradeBuilder final : public TestCustomElementDefinitionBuilder {
 
   CustomElementDefinition* Build(const CustomElementDescriptor& descriptor,
                                  CustomElementDefinition::Id) override {
-    return new LogUpgradeDefinition(descriptor);
+    return MakeGarbageCollected<LogUpgradeDefinition>(descriptor);
   }
 
   DISALLOW_COPY_AND_ASSIGN(LogUpgradeBuilder);
@@ -276,15 +277,16 @@ TEST_F(CustomElementRegistryTest, define_upgradesInDocumentElements) {
 
   Element* element = CreateElement("a-a").InDocument(&GetDocument());
   element->setAttribute(
-      QualifiedName(g_null_atom, "attr1", HTMLNames::xhtmlNamespaceURI), "v1");
-  element->SetBooleanAttribute(HTMLNames::contenteditableAttr, true);
+      QualifiedName(g_null_atom, "attr1", html_names::xhtmlNamespaceURI), "v1");
+  element->SetBooleanAttribute(html_names::kContenteditableAttr, true);
   GetDocument().documentElement()->AppendChild(element);
 
   LogUpgradeBuilder builder;
   NonThrowableExceptionState should_not_throw;
   {
     CEReactionsScope reactions;
-    Define("a-a", builder, ElementDefinitionOptions(), should_not_throw);
+    Define("a-a", builder, ElementDefinitionOptions::Create(),
+           should_not_throw);
   }
   LogUpgradeDefinition* definition =
       static_cast<LogUpgradeDefinition*>(Registry().DefinitionForName("a-a"));
@@ -326,7 +328,8 @@ TEST_F(CustomElementRegistryTest, attributeChangedCallback) {
   NonThrowableExceptionState should_not_throw;
   {
     CEReactionsScope reactions;
-    Define("a-a", builder, ElementDefinitionOptions(), should_not_throw);
+    Define("a-a", builder, ElementDefinitionOptions::Create(),
+           should_not_throw);
   }
   LogUpgradeDefinition* definition =
       static_cast<LogUpgradeDefinition*>(Registry().DefinitionForName("a-a"));
@@ -335,7 +338,7 @@ TEST_F(CustomElementRegistryTest, attributeChangedCallback) {
   {
     CEReactionsScope reactions;
     element->setAttribute(
-        QualifiedName(g_null_atom, "attr2", HTMLNames::xhtmlNamespaceURI),
+        QualifiedName(g_null_atom, "attr2", html_names::xhtmlNamespaceURI),
         "v2");
   }
   EXPECT_EQ(LogUpgradeDefinition::kAttributeChangedCallback,
@@ -361,7 +364,8 @@ TEST_F(CustomElementRegistryTest, disconnectedCallback) {
   NonThrowableExceptionState should_not_throw;
   {
     CEReactionsScope reactions;
-    Define("a-a", builder, ElementDefinitionOptions(), should_not_throw);
+    Define("a-a", builder, ElementDefinitionOptions::Create(),
+           should_not_throw);
   }
   LogUpgradeDefinition* definition =
       static_cast<LogUpgradeDefinition*>(Registry().DefinitionForName("a-a"));
@@ -388,7 +392,8 @@ TEST_F(CustomElementRegistryTest, adoptedCallback) {
   NonThrowableExceptionState should_not_throw;
   {
     CEReactionsScope reactions;
-    Define("a-a", builder, ElementDefinitionOptions(), should_not_throw);
+    Define("a-a", builder, ElementDefinitionOptions::Create(),
+           should_not_throw);
   }
   LogUpgradeDefinition* definition =
       static_cast<LogUpgradeDefinition*>(Registry().DefinitionForName("a-a"));
@@ -417,10 +422,10 @@ TEST_F(CustomElementRegistryTest, adoptedCallback) {
 TEST_F(CustomElementRegistryTest, lookupCustomElementDefinition) {
   NonThrowableExceptionState should_not_throw;
   TestCustomElementDefinitionBuilder builder;
-  CustomElementDefinition* definition_a =
-      Define("a-a", builder, ElementDefinitionOptions(), should_not_throw);
-  ElementDefinitionOptions options;
-  options.setExtends("div");
+  CustomElementDefinition* definition_a = Define(
+      "a-a", builder, ElementDefinitionOptions::Create(), should_not_throw);
+  ElementDefinitionOptions* options = ElementDefinitionOptions::Create();
+  options->setExtends("div");
   CustomElementDefinition* definition_b =
       Define("b-b", builder, options, should_not_throw);
   // look up defined autonomous custom element
@@ -451,8 +456,8 @@ TEST_F(CustomElementRegistryTest, DefineEmbedderCustomElements) {
   NonThrowableExceptionState should_not_throw;
   TestCustomElementDefinitionBuilder builder;
   CustomElementDefinition* definition_embedder =
-      Define("embeddercustomelement", builder, ElementDefinitionOptions(),
-             should_not_throw);
+      Define("embeddercustomelement", builder,
+             ElementDefinitionOptions::Create(), should_not_throw);
   CustomElementDefinition* definition =
       Registry().DefinitionFor(CustomElementDescriptor(
           "embeddercustomelement", "embeddercustomelement"));
@@ -473,8 +478,8 @@ TEST_F(CustomElementRegistryTest, DisallowedEmbedderCustomElements) {
 
   TestCustomElementDefinitionBuilder builder;
   CustomElementDefinition* definition_embedder =
-      Define("embeddercustomelement", builder, ElementDefinitionOptions(),
-             IGNORE_EXCEPTION_FOR_TESTING);
+      Define("embeddercustomelement", builder,
+             ElementDefinitionOptions::Create(), IGNORE_EXCEPTION_FOR_TESTING);
   CustomElementDefinition* definition =
       Registry().DefinitionFor(CustomElementDescriptor(
           "embeddercustomelement", "embeddercustomelement"));
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_test.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element_test.cc
index 97f0af76e0b..349c7931623 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_test.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_test.cc
@@ -199,12 +199,12 @@ TEST(CustomElementTest, StateByCreateElement) {
     EXPECT_EQ(data.state, element->GetCustomElementState()) << data.name;
     EXPECT_EQ(data.v0state, element->GetV0CustomElementState()) << data.name;
 
-    element = document.createElementNS(HTMLNames::xhtmlNamespaceURI, data.name,
+    element = document.createElementNS(html_names::xhtmlNamespaceURI, data.name,
                                        ASSERT_NO_EXCEPTION);
     EXPECT_EQ(data.state, element->GetCustomElementState()) << data.name;
     EXPECT_EQ(data.v0state, element->GetV0CustomElementState()) << data.name;
 
-    element = document.createElementNS(SVGNames::svgNamespaceURI, data.name,
+    element = document.createElementNS(svg_names::kNamespaceURI, data.name,
                                        ASSERT_NO_EXCEPTION);
     EXPECT_EQ(CustomElementState::kUncustomized,
               element->GetCustomElementState())
@@ -225,7 +225,8 @@ TEST(CustomElementTest,
     CEReactionsScope reactions;
     TestCustomElementDefinitionBuilder builder;
     registry->DefineInternal(script_state, "a-a", builder,
-                             ElementDefinitionOptions(), should_not_throw);
+                             ElementDefinitionOptions::Create(),
+                             should_not_throw);
   }
   CustomElementDefinition* definition =
       registry->DefinitionFor(CustomElementDescriptor("a-a", "a-a"));
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_test_helpers.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element_test_helpers.cc
index 37ee736cf49..87b6f04aa50 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_test_helpers.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_test_helpers.cc
@@ -9,7 +9,7 @@ namespace blink {
 CustomElementDefinition* TestCustomElementDefinitionBuilder::Build(
     const CustomElementDescriptor& descriptor,
     CustomElementDefinition::Id) {
-  return new TestCustomElementDefinition(descriptor);
+  return MakeGarbageCollected<TestCustomElementDefinition>(descriptor);
 }
 
 }  // namespace blink
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_test_helpers.h b/chromium/third_party/blink/renderer/core/html/custom/custom_element_test_helpers.h
index 97d6c590de2..9f6b8183ad8 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_test_helpers.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_test_helpers.h
@@ -49,9 +49,12 @@ class TestCustomElementDefinition : public CustomElementDefinition {
       : CustomElementDefinition(descriptor) {}
 
   TestCustomElementDefinition(const CustomElementDescriptor& descriptor,
-                              HashSet<AtomicString>&& observed_attributes)
+                              HashSet<AtomicString>&& observed_attributes,
+                              const Vector<String>& disabled_features)
       : CustomElementDefinition(descriptor,
-                                std::move(observed_attributes)) {}
+                                std::move(observed_attributes),
+                                disabled_features,
+                                FormAssociationFlag::kNo) {}
 
   ~TestCustomElementDefinition() override = default;
 
@@ -74,6 +77,8 @@ class TestCustomElementDefinition : public CustomElementDefinition {
   bool HasConnectedCallback() const override { return false; }
   bool HasDisconnectedCallback() const override { return false; }
   bool HasAdoptedCallback() const override { return false; }
+  bool HasFormAssociatedCallback() const override { return false; }
+  bool HasDisabledStateChangedCallback() const override { return false; }
 
   void RunConnectedCallback(Element*) override {
     NOTREACHED() << "definition does not have connected callback";
@@ -95,6 +100,14 @@ class TestCustomElementDefinition : public CustomElementDefinition {
                                    const AtomicString& new_value) override {
     NOTREACHED() << "definition does not have attribute changed callback";
   }
+  void RunFormAssociatedCallback(Element* element,
+                                 HTMLFormElement* nullable_form) override {
+    NOTREACHED() << "definition does not have formAssociatedCallback";
+  }
+  void RunDisabledStateChangedCallback(Element* element,
+                                       bool is_disabled) override {
+    NOTREACHED() << "definition does not have disabledStateChangedCallback";
+  }
 
   DISALLOW_COPY_AND_ASSIGN(TestCustomElementDefinition);
 };
@@ -104,7 +117,8 @@ class CreateElement {
 
  public:
   CreateElement(const AtomicString& local_name)
-      : namespace_uri_(HTMLNames::xhtmlNamespaceURI), local_name_(local_name) {}
+      : namespace_uri_(html_names::xhtmlNamespaceURI),
+        local_name_(local_name) {}
 
   CreateElement& InDocument(Document* document) {
     document_ = document;
@@ -117,7 +131,7 @@ class CreateElement {
   }
 
   CreateElement& WithId(const AtomicString& id) {
-    attributes_.push_back(std::make_pair(HTMLNames::idAttr, id));
+    attributes_.push_back(std::make_pair(html_names::kIdAttr, id));
     return *this;
   }
 
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_upgrade_sorter.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element_upgrade_sorter.cc
index 8c2d88e956a..0e045400c20 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_upgrade_sorter.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_upgrade_sorter.cc
@@ -15,8 +15,8 @@
 namespace blink {
 
 CustomElementUpgradeSorter::CustomElementUpgradeSorter()
-    : elements_(new HeapHashSet<Member<Element>>()),
-      parent_child_map_(new ParentChildMap()) {}
+    : elements_(MakeGarbageCollected<HeapHashSet<Member<Element>>>()),
+      parent_child_map_(MakeGarbageCollected<ParentChildMap>()) {}
 
 static HTMLLinkElement* GetLinkElementForImport(const Document& import) {
   if (HTMLImportLoader* loader = import.ImportLoader())
@@ -33,7 +33,7 @@ CustomElementUpgradeSorter::AddToParentChildMap(Node* parent, Node* child) {
     return kParentAlreadyExistsInMap;
   }
 
-  ChildSet* child_set = new ChildSet();
+  ChildSet* child_set = MakeGarbageCollected<ChildSet>();
   child_set->insert(child);
   result.stored_value->value = child_set;
   return kParentAddedToMap;
diff --git a/chromium/third_party/blink/renderer/core/html/custom/custom_element_upgrade_sorter_test.cc b/chromium/third_party/blink/renderer/core/html/custom/custom_element_upgrade_sorter_test.cc
index 431aa916d10..93808872260 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/custom_element_upgrade_sorter_test.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/custom_element_upgrade_sorter_test.cc
@@ -6,7 +6,7 @@
 
 #include <memory>
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/blink/renderer/bindings/core/v8/string_or_dictionary.h"
+#include "third_party/blink/renderer/bindings/core/v8/string_or_element_creation_options.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_binding_for_core.h"
 #include "third_party/blink/renderer/core/dom/document.h"
 #include "third_party/blink/renderer/core/dom/element.h"
@@ -28,8 +28,8 @@ class CustomElementUpgradeSorterTest : public PageTestBase {
   Element* CreateElementWithId(const char* local_name, const char* id) {
     NonThrowableExceptionState no_exceptions;
     Element* element = GetDocument().CreateElementForBinding(
-        local_name, StringOrDictionary(), no_exceptions);
-    element->setAttribute(HTMLNames::idAttr, id);
+        local_name, StringOrElementCreationOptions(), no_exceptions);
+    element->setAttribute(html_names::kIdAttr, id);
     return element;
   }
 
@@ -41,7 +41,7 @@ class CustomElementUpgradeSorterTest : public PageTestBase {
 TEST_F(CustomElementUpgradeSorterTest, inOtherDocument_notInSet) {
   NonThrowableExceptionState no_exceptions;
   Element* element = GetDocument().CreateElementForBinding(
-      "a-a", StringOrDictionary(), no_exceptions);
+      "a-a", StringOrElementCreationOptions(), no_exceptions);
 
   Document* other_document = HTMLDocument::CreateForTest();
   other_document->AppendChild(element);
@@ -60,7 +60,7 @@ TEST_F(CustomElementUpgradeSorterTest, inOtherDocument_notInSet) {
 TEST_F(CustomElementUpgradeSorterTest, oneCandidate) {
   NonThrowableExceptionState no_exceptions;
   Element* element = GetDocument().CreateElementForBinding(
-      "a-a", StringOrDictionary(), no_exceptions);
+      "a-a", StringOrElementCreationOptions(), no_exceptions);
   GetDocument().documentElement()->AppendChild(element);
 
   CustomElementUpgradeSorter sorter;
diff --git a/chromium/third_party/blink/renderer/core/html/custom/element_internals.cc b/chromium/third_party/blink/renderer/core/html/custom/element_internals.cc
new file mode 100644
index 00000000000..3d14c75c849
--- /dev/null
+++ b/chromium/third_party/blink/renderer/core/html/custom/element_internals.cc
@@ -0,0 +1,117 @@
+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "third_party/blink/renderer/core/html/custom/element_internals.h"
+
+#include "third_party/blink/renderer/core/dom/node_lists_node_data.h"
+#include "third_party/blink/renderer/core/fileapi/file.h"
+#include "third_party/blink/renderer/core/html/custom/custom_element.h"
+#include "third_party/blink/renderer/core/html/forms/form_data.h"
+#include "third_party/blink/renderer/core/html/forms/html_form_element.h"
+#include "third_party/blink/renderer/core/html/html_element.h"
+
+namespace blink {
+
+ElementInternals::ElementInternals(HTMLElement& target) : target_(target) {
+  value_.SetUSVString(String());
+}
+
+void ElementInternals::Trace(Visitor* visitor) {
+  visitor->Trace(target_);
+  visitor->Trace(value_);
+  visitor->Trace(entry_source_);
+  ListedElement::Trace(visitor);
+  ScriptWrappable::Trace(visitor);
+}
+
+void ElementInternals::setFormValue(const FileOrUSVString& value,
+                                    ExceptionState& exception_state) {
+  setFormValue(value, nullptr, exception_state);
+}
+
+void ElementInternals::setFormValue(const FileOrUSVString& value,
+                                    FormData* entry_source,
+                                    ExceptionState& exception_state) {
+  if (!Target().IsFormAssociatedCustomElement()) {
+    exception_state.ThrowDOMException(
+        DOMExceptionCode::kInvalidStateError,
+        "The target element is not a form-associated custom element.");
+    return;
+  }
+  if (!entry_source || entry_source->size() == 0u) {
+    value_ = value;
+    entry_source_ = nullptr;
+    return;
+  }
+  value_ = value;
+  entry_source_ = MakeGarbageCollected<FormData>(*entry_source);
+}
+
+HTMLFormElement* ElementInternals::form(ExceptionState& exception_state) const {
+  if (!Target().IsFormAssociatedCustomElement()) {
+    exception_state.ThrowDOMException(
+        DOMExceptionCode::kInvalidStateError,
+        "The target element is not a form-associated custom element.");
+    return nullptr;
+  }
+  return ListedElement::Form();
+}
+
+void ElementInternals::DidUpgrade() {
+  ContainerNode* parent = Target().parentNode();
+  if (!parent)
+    return;
+  InsertedInto(*parent);
+  if (auto* owner_form = Form()) {
+    if (auto* lists = owner_form->NodeLists())
+      lists->InvalidateCaches(nullptr);
+  }
+  for (ContainerNode* node = parent; node; node = node->parentNode()) {
+    if (IsHTMLFieldSetElement(node)) {
+      // TODO(tkent): Invalidate only HTMLFormControlsCollections.
+      if (auto* lists = node->NodeLists())
+        lists->InvalidateCaches(nullptr);
+    }
+  }
+}
+
+bool ElementInternals::IsFormControlElement() const {
+  return false;
+}
+
+bool ElementInternals::IsElementInternals() const {
+  return true;
+}
+
+bool ElementInternals::IsEnumeratable() const {
+  return true;
+}
+
+void ElementInternals::AppendToFormData(FormData& form_data) {
+  const AtomicString& name = Target().FastGetAttribute(html_names::kNameAttr);
+  if (!entry_source_ || entry_source_->size() == 0u) {
+    if (name.IsNull())
+      return;
+    if (value_.IsFile())
+      form_data.AppendFromElement(name, value_.GetAsFile());
+    else if (value_.IsUSVString())
+      form_data.AppendFromElement(name, value_.GetAsUSVString());
+    else
+      form_data.AppendFromElement(name, g_empty_string);
+    return;
+  }
+  for (const auto& entry : entry_source_->Entries()) {
+    if (entry->isFile())
+      form_data.append(entry->name(), entry->GetFile());
+    else
+      form_data.append(entry->name(), entry->Value());
+  }
+}
+
+void ElementInternals::DidChangeForm() {
+  ListedElement::DidChangeForm();
+  CustomElement::EnqueueFormAssociatedCallback(Target(), Form());
+}
+
+}  // namespace blink
diff --git a/chromium/third_party/blink/renderer/core/html/custom/element_internals.h b/chromium/third_party/blink/renderer/core/html/custom/element_internals.h
new file mode 100644
index 00000000000..d32036402cd
--- /dev/null
+++ b/chromium/third_party/blink/renderer/core/html/custom/element_internals.h
@@ -0,0 +1,60 @@
+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_HTML_CUSTOM_ELEMENT_INTERNALS_H_
+#define THIRD_PARTY_BLINK_RENDERER_CORE_HTML_CUSTOM_ELEMENT_INTERNALS_H_
+
+#include "third_party/blink/renderer/bindings/core/v8/file_or_usv_string.h"
+#include "third_party/blink/renderer/core/html/forms/listed_element.h"
+#include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
+#include "third_party/blink/renderer/platform/wtf/casting.h"
+
+namespace blink {
+
+class HTMLElement;
+
+class ElementInternals : public ScriptWrappable, public ListedElement {
+  DEFINE_WRAPPERTYPEINFO();
+  USING_GARBAGE_COLLECTED_MIXIN(ElementInternals);
+
+ public:
+  ElementInternals(HTMLElement& target);
+  void Trace(Visitor* visitor) override;
+
+  HTMLElement& Target() const { return *target_; }
+  void DidUpgrade();
+
+  // IDL attributes/operations
+  void setFormValue(const FileOrUSVString& value,
+                    ExceptionState& exception_state);
+  void setFormValue(const FileOrUSVString& value,
+                    FormData* entry_source,
+                    ExceptionState& exception_state);
+  HTMLFormElement* form(ExceptionState& exception_state) const;
+
+ private:
+  // ListedElement overrides:
+  bool IsFormControlElement() const override;
+  bool IsElementInternals() const override;
+  bool IsEnumeratable() const override;
+  void AppendToFormData(FormData& form_data) override;
+  void DidChangeForm() override;
+
+  Member<HTMLElement> target_;
+
+  FileOrUSVString value_;
+  Member<FormData> entry_source_;
+
+  DISALLOW_COPY_AND_ASSIGN(ElementInternals);
+};
+
+template <>
+struct DowncastTraits<ElementInternals> {
+  static bool AllowFrom(const ListedElement& listed_element) {
+    return listed_element.IsElementInternals();
+  }
+};
+
+}  // namespace blink
+#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_HTML_CUSTOM_ELEMENT_INTERNALS_H_
diff --git a/chromium/third_party/blink/renderer/core/html/custom/element_internals.idl b/chromium/third_party/blink/renderer/core/html/custom/element_internals.idl
new file mode 100644
index 00000000000..c918fba298d
--- /dev/null
+++ b/chromium/third_party/blink/renderer/core/html/custom/element_internals.idl
@@ -0,0 +1,16 @@
+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// https://docs.google.com/document/d/1JO8puctCSpW-ZYGU8lF-h4FWRIDQNDVexzHoOQ2iQmY/edit?pli=1#heading=h.pjt9nhs3gu3k
+
+[
+  Exposed=Window,
+  RuntimeEnabled=ElementInternals
+]
+interface ElementInternals {
+  // Attributes and operations for form-associated custom elements.
+  [RaisesException] void setFormValue(FormDataEntryValue value, optional FormData entrySource);
+  [RaisesException] readonly attribute HTMLFormElement? form;
+};
+
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element.cc b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element.cc
index 4901ae8926c..4e10b8db5ee 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element.cc
@@ -73,7 +73,7 @@ bool V0CustomElement::IsValidName(const AtomicString& name) {
     DEFINE_STATIC_LOCAL(Vector<AtomicString>, reserved_names, ());
     if (reserved_names.IsEmpty()) {
       // FIXME(crbug.com/426605): We should be able to remove this.
-      reserved_names.push_back(MathMLNames::annotation_xmlTag.LocalName());
+      reserved_names.push_back(mathml_names::kAnnotationXmlTag.LocalName());
     }
 
     if (kNotFound == reserved_names.Find(name))
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_async_import_microtask_queue.h b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_async_import_microtask_queue.h
index f3476bc2e81..331eb3fd049 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_async_import_microtask_queue.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_async_import_microtask_queue.h
@@ -39,13 +39,14 @@ class V0CustomElementAsyncImportMicrotaskQueue
     : public V0CustomElementMicrotaskQueueBase {
  public:
   static V0CustomElementAsyncImportMicrotaskQueue* Create() {
-    return new V0CustomElementAsyncImportMicrotaskQueue();
+    return MakeGarbageCollected<V0CustomElementAsyncImportMicrotaskQueue>();
   }
 
+  V0CustomElementAsyncImportMicrotaskQueue() = default;
+
   void Enqueue(V0CustomElementMicrotaskStep*);
 
  private:
-  V0CustomElementAsyncImportMicrotaskQueue() = default;
   void DoDispatch() override;
 };
 
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_callback_queue.cc b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_callback_queue.cc
index f7a744a580b..c4de24bce0c 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_callback_queue.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_callback_queue.cc
@@ -36,7 +36,7 @@ namespace blink {
 
 V0CustomElementCallbackQueue* V0CustomElementCallbackQueue::Create(
     Element* element) {
-  return new V0CustomElementCallbackQueue(element);
+  return MakeGarbageCollected<V0CustomElementCallbackQueue>(element);
 }
 
 V0CustomElementCallbackQueue::V0CustomElementCallbackQueue(Element* element)
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_callback_queue.h b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_callback_queue.h
index 370954e4724..529e1c09d91 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_callback_queue.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_callback_queue.h
@@ -46,6 +46,8 @@ class V0CustomElementCallbackQueue
  public:
   static V0CustomElementCallbackQueue* Create(Element*);
 
+  explicit V0CustomElementCallbackQueue(Element*);
+
   typedef int ElementQueueId;
   ElementQueueId Owner() const { return owner_; }
 
@@ -66,8 +68,6 @@ class V0CustomElementCallbackQueue
   void Trace(blink::Visitor*);
 
  private:
-  explicit V0CustomElementCallbackQueue(Element*);
-
   Member<Element> element_;
   HeapVector<Member<V0CustomElementProcessingStep>> queue_;
   ElementQueueId owner_;
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_definition.cc b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_definition.cc
index 3ac97190502..d7f446b42f0 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_definition.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_definition.cc
@@ -35,7 +35,7 @@ namespace blink {
 V0CustomElementDefinition* V0CustomElementDefinition::Create(
     const V0CustomElementDescriptor& descriptor,
     V0CustomElementLifecycleCallbacks* callbacks) {
-  return new V0CustomElementDefinition(descriptor, callbacks);
+  return MakeGarbageCollected<V0CustomElementDefinition>(descriptor, callbacks);
 }
 
 V0CustomElementDefinition::V0CustomElementDefinition(
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_definition.h b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_definition.h
index f1ece759b56..6b5806d85a3 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_definition.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_definition.h
@@ -42,6 +42,9 @@ class V0CustomElementDefinition final
   static V0CustomElementDefinition* Create(const V0CustomElementDescriptor&,
                                            V0CustomElementLifecycleCallbacks*);
 
+  V0CustomElementDefinition(const V0CustomElementDescriptor&,
+                            V0CustomElementLifecycleCallbacks*);
+
   const V0CustomElementDescriptor& Descriptor() const { return descriptor_; }
   V0CustomElementLifecycleCallbacks* Callbacks() const {
     return callbacks_.Get();
@@ -50,9 +53,6 @@ class V0CustomElementDefinition final
   void Trace(blink::Visitor*);
 
  private:
-  V0CustomElementDefinition(const V0CustomElementDescriptor&,
-                            V0CustomElementLifecycleCallbacks*);
-
   V0CustomElementDescriptor descriptor_;
   Member<V0CustomElementLifecycleCallbacks> callbacks_;
 };
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_import_step.h b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_import_step.h
index 3888a2f5e2c..eb152f5d3a6 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_import_step.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_import_step.h
@@ -49,9 +49,10 @@ class V0CustomElementMicrotaskImportStep final
     : public V0CustomElementMicrotaskStep {
  public:
   static V0CustomElementMicrotaskImportStep* Create(HTMLImportChild* import) {
-    return new V0CustomElementMicrotaskImportStep(import);
+    return MakeGarbageCollected<V0CustomElementMicrotaskImportStep>(import);
   }
 
+  explicit V0CustomElementMicrotaskImportStep(HTMLImportChild*);
   ~V0CustomElementMicrotaskImportStep() override;
 
   // API for HTML Imports
@@ -61,8 +62,6 @@ class V0CustomElementMicrotaskImportStep final
   void Trace(blink::Visitor*) override;
 
  private:
-  explicit V0CustomElementMicrotaskImportStep(HTMLImportChild*);
-
   void DidUpgradeAllCustomElements();
   bool ShouldWaitForImport() const;
 
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_resolution_step.cc b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_resolution_step.cc
index 5a0224dea7d..eed62964c73 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_resolution_step.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_resolution_step.cc
@@ -40,8 +40,8 @@ V0CustomElementMicrotaskResolutionStep::Create(
     V0CustomElementRegistrationContext* context,
     Element* element,
     const V0CustomElementDescriptor& descriptor) {
-  return new V0CustomElementMicrotaskResolutionStep(context, element,
-                                                    descriptor);
+  return MakeGarbageCollected<V0CustomElementMicrotaskResolutionStep>(
+      context, element, descriptor);
 }
 
 V0CustomElementMicrotaskResolutionStep::V0CustomElementMicrotaskResolutionStep(
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_resolution_step.h b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_resolution_step.h
index 000de7da616..83bb565de1d 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_resolution_step.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_resolution_step.h
@@ -48,15 +48,14 @@ class V0CustomElementMicrotaskResolutionStep final
       Element*,
       const V0CustomElementDescriptor&);
 
+  V0CustomElementMicrotaskResolutionStep(V0CustomElementRegistrationContext*,
+                                         Element*,
+                                         const V0CustomElementDescriptor&);
   ~V0CustomElementMicrotaskResolutionStep() override;
 
   void Trace(blink::Visitor*) override;
 
  private:
-  V0CustomElementMicrotaskResolutionStep(V0CustomElementRegistrationContext*,
-                                         Element*,
-                                         const V0CustomElementDescriptor&);
-
   Result Process() override;
 
 #if !defined(NDEBUG)
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_run_queue.h b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_run_queue.h
index 92c4c36273d..9ac97493dd2 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_run_queue.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_microtask_run_queue.h
@@ -18,9 +18,11 @@ class V0CustomElementMicrotaskRunQueue
     : public GarbageCollected<V0CustomElementMicrotaskRunQueue> {
  public:
   static V0CustomElementMicrotaskRunQueue* Create() {
-    return new V0CustomElementMicrotaskRunQueue;
+    return MakeGarbageCollected<V0CustomElementMicrotaskRunQueue>();
   }
 
+  V0CustomElementMicrotaskRunQueue();
+
   void Enqueue(HTMLImportLoader* parent_loader,
                V0CustomElementMicrotaskStep*,
                bool import_is_sync);
@@ -30,8 +32,6 @@ class V0CustomElementMicrotaskRunQueue
   void Trace(blink::Visitor*);
 
  private:
-  V0CustomElementMicrotaskRunQueue();
-
   void Dispatch();
 
   Member<V0CustomElementSyncMicrotaskQueue> sync_queue_;
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_observer.cc b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_observer.cc
index 637440bde08..a450e7667cf 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_observer.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_observer.cc
@@ -42,7 +42,7 @@ typedef HeapHashMap<WeakMember<Element>, Member<V0CustomElementObserver>>
 
 static ElementObserverMap& ElementObservers() {
   DEFINE_STATIC_LOCAL(Persistent<ElementObserverMap>, map,
-                      (new ElementObserverMap));
+                      (MakeGarbageCollected<ElementObserverMap>()));
   return *map;
 }
 
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_registration_context.cc b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_registration_context.cc
index 9fa081ea367..73ad40a0bec 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_registration_context.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_registration_context.cc
@@ -76,9 +76,9 @@ Element* V0CustomElementRegistrationContext::CreateCustomTagElement(
 
   Element* element;
 
-  if (HTMLNames::xhtmlNamespaceURI == tag_name.NamespaceURI()) {
+  if (html_names::xhtmlNamespaceURI == tag_name.NamespaceURI()) {
     element = HTMLElement::Create(tag_name, document);
-  } else if (SVGNames::svgNamespaceURI == tag_name.NamespaceURI()) {
+  } else if (svg_names::kNamespaceURI == tag_name.NamespaceURI()) {
     element = SVGUnknownElement::Create(tag_name, document);
   } else {
     // XML elements are not custom elements, so return early.
@@ -132,7 +132,7 @@ void V0CustomElementRegistrationContext::SetIsAttributeAndTypeExtension(
     const AtomicString& type) {
   DCHECK(element);
   DCHECK(!type.IsEmpty());
-  element->setAttribute(HTMLNames::isAttr, type);
+  element->setAttribute(html_names::kIsAttr, type);
   SetTypeExtension(element, type);
 }
 
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_registration_context.h b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_registration_context.h
index 52f2b66497f..fbdc75506d9 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_registration_context.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_registration_context.h
@@ -46,9 +46,10 @@ class V0CustomElementRegistrationContext final
     : public GarbageCollectedFinalized<V0CustomElementRegistrationContext> {
  public:
   static V0CustomElementRegistrationContext* Create() {
-    return new V0CustomElementRegistrationContext();
+    return MakeGarbageCollected<V0CustomElementRegistrationContext>();
   }
 
+  V0CustomElementRegistrationContext();
   ~V0CustomElementRegistrationContext() = default;
   void DocumentWasDetached() { registry_.DocumentWasDetached(); }
 
@@ -70,9 +71,6 @@ class V0CustomElementRegistrationContext final
 
   void Trace(blink::Visitor*);
 
- protected:
-  V0CustomElementRegistrationContext();
-
   // Instance creation
   void DidGiveTypeExtension(Element*, const AtomicString& type);
 
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_registry.cc b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_registry.cc
index 40de265ccfd..eccbfad76d2 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_registry.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_registry.cc
@@ -73,8 +73,8 @@ V0CustomElementDefinition* V0CustomElementRegistry::RegisterElement(
   if (!constructor_builder->ValidateOptions(type, tag_name, exception_state))
     return nullptr;
 
-  DCHECK(tag_name.NamespaceURI() == HTMLNames::xhtmlNamespaceURI ||
-         tag_name.NamespaceURI() == SVGNames::svgNamespaceURI);
+  DCHECK(tag_name.NamespaceURI() == html_names::xhtmlNamespaceURI ||
+         tag_name.NamespaceURI() == svg_names::kNamespaceURI);
 
   DCHECK(!document_was_detached_);
 
@@ -109,7 +109,7 @@ V0CustomElementDefinition* V0CustomElementRegistry::RegisterElement(
     return nullptr;
   }
 
-  if (tag_name.NamespaceURI() == SVGNames::svgNamespaceURI) {
+  if (tag_name.NamespaceURI() == svg_names::kNamespaceURI) {
     UseCounter::Count(document,
                       WebFeature::kV0CustomElementsRegisterSVGElement);
   } else {
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_scheduler.cc b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_scheduler.cc
index 42c3237e97c..7a8ba361b0c 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_scheduler.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_scheduler.cc
@@ -52,7 +52,7 @@ typedef HeapHashMap<Member<Element>, Member<V0CustomElementCallbackQueue>>
 
 static ElementCallbackQueueMap& CallbackQueues() {
   DEFINE_STATIC_LOCAL(Persistent<ElementCallbackQueueMap>, map,
-                      (new ElementCallbackQueueMap));
+                      (MakeGarbageCollected<ElementCallbackQueueMap>()));
   return *map;
 }
 
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_sync_microtask_queue.h b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_sync_microtask_queue.h
index 0385acf794c..ecc502b9ce0 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_sync_microtask_queue.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_sync_microtask_queue.h
@@ -13,13 +13,14 @@ class V0CustomElementSyncMicrotaskQueue
     : public V0CustomElementMicrotaskQueueBase {
  public:
   static V0CustomElementSyncMicrotaskQueue* Create() {
-    return new V0CustomElementSyncMicrotaskQueue();
+    return MakeGarbageCollected<V0CustomElementSyncMicrotaskQueue>();
   }
 
+  V0CustomElementSyncMicrotaskQueue() = default;
+
   void Enqueue(V0CustomElementMicrotaskStep*);
 
  private:
-  V0CustomElementSyncMicrotaskQueue() = default;
   void DoDispatch() override;
 };
 
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_upgrade_candidate_map.cc b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_upgrade_candidate_map.cc
index 72e0c7757ed..a74a1b2ae3d 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_upgrade_candidate_map.cc
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_upgrade_candidate_map.cc
@@ -36,7 +36,7 @@ namespace blink {
 
 V0CustomElementUpgradeCandidateMap*
 V0CustomElementUpgradeCandidateMap::Create() {
-  return new V0CustomElementUpgradeCandidateMap();
+  return MakeGarbageCollected<V0CustomElementUpgradeCandidateMap>();
 }
 
 V0CustomElementUpgradeCandidateMap::~V0CustomElementUpgradeCandidateMap() =
@@ -55,7 +55,8 @@ void V0CustomElementUpgradeCandidateMap::Add(
       unresolved_definitions_.find(descriptor);
   ElementSet* elements;
   if (it == unresolved_definitions_.end())
-    elements = unresolved_definitions_.insert(descriptor, new ElementSet())
+    elements = unresolved_definitions_
+                   .insert(descriptor, MakeGarbageCollected<ElementSet>())
                    .stored_value->value.Get();
   else
     elements = it->value.Get();
diff --git a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_upgrade_candidate_map.h b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_upgrade_candidate_map.h
index df4169720f4..de500414000 100644
--- a/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_upgrade_candidate_map.h
+++ b/chromium/third_party/blink/renderer/core/html/custom/v0_custom_element_upgrade_candidate_map.h
@@ -44,6 +44,8 @@ class V0CustomElementUpgradeCandidateMap final
     : public V0CustomElementObserver {
  public:
   static V0CustomElementUpgradeCandidateMap* Create();
+
+  V0CustomElementUpgradeCandidateMap() = default;
   ~V0CustomElementUpgradeCandidateMap() override;
 
   // API for V0CustomElementRegistrationContext to save and take candidates
@@ -56,8 +58,6 @@ class V0CustomElementUpgradeCandidateMap final
   void Trace(blink::Visitor*) override;
 
  private:
-  V0CustomElementUpgradeCandidateMap() = default;
-
   void ElementWasDestroyed(Element*) override;
 
   typedef HeapHashMap<WeakMember<Element>, V0CustomElementDescriptor>