BASELINE: Update Chromium to 80.0.3987.136

Change-Id: I98e1649aafae85ba3a83e67af00bb27ef301db7b
Reviewed-by: Jüri Valdmann <juri.valdmann@qt.io>

2 files changed, 38 insertions, 11 deletions

diff --git a/chromium/styleguide/c++/c++-dos-and-donts.md b/chromium/styleguide/c++/c++-dos-and-donts.md
index 1b5b25419af..f7906662224 100644
--- a/chromium/styleguide/c++/c++-dos-and-donts.md
+++ b/chromium/styleguide/c++/c++-dos-and-donts.md
@@ -37,6 +37,23 @@ void foo() {
 }
 ```
 
+## Explicitly declare class copyability/movability
+
+The
+[Google Style Guide](http://google.github.io/styleguide/cppguide.html#Copyable_Movable_Types)
+says classes can omit copy/move declarations or deletions "only if they are
+obvious".  Because "obvious" is subjective and even the examples in the style
+guide take some thought to figure out, being explicit is clear, simple, and
+avoids any risk of accidental copying.
+
+Declare or delete these operations in the public section, between other
+constructors and the destructor; `DISALLOW_COPY_AND_ASSIGN` is deprecated.  For
+a non-copyable/movable type, delete the copy operations (the move operations
+will be implicitly deleted); otherwise, declare either copy operations, move
+operations, or both (a non-declared pair will be implicitly deleted).  Always
+declare or delete both construction and assignment, not just one (which can
+introduce subtle bugs).
+
 ## Variable initialization
 
 There are myriad ways to initialize variables in C++11.  Prefer the following
@@ -263,3 +280,9 @@ The common ways to represent names in comments are as follows:
 // FooImpl implements the FooBase class.
 // FooFunction() modifies |foo_member_|.
 ```
+
+## Named namespaces
+
+Named namespaces are discouraged in top-level embedders (e.g., `chrome/`). See
+[this thread](https://groups.google.com/a/chromium.org/d/msg/chromium-dev/8ROncnL1t4k/J7uJMCQ8BwAJ)
+for background and discussion.
diff --git a/chromium/styleguide/web/web.md b/chromium/styleguide/web/web.md
index 62e86bf20dc..414b8153ae9 100644
--- a/chromium/styleguide/web/web.md
+++ b/chromium/styleguide/web/web.md
@@ -207,8 +207,7 @@ compatibility issues are less relevant for Chrome-only code).
 
 * Alphabetize properties.
     * `-webkit` properties should be listed at the top, sorted alphabetically.
-    * `--variables` and `--mixins: {}` should be alphabetically declared when
-      possible.
+    * `--variables` should be alphabetically declared when possible.
 
 * Insert a space after the colon separating property and value.
 
@@ -241,6 +240,16 @@ compatibility issues are less relevant for Chrome-only code).
 * Use scalable `font-size` units like `%` or `em` to respect users' default font
   size
 
+* Don't use CSS Mixins (`--mixin: {}` or `@apply --mixin;`) in new code. [We're
+  removing them.](https://crbug.com/973674)
+    * Mixins were [dropped from CSS](https://www.xanthir.com/b4o00) in favor of
+      [CSS Shadow Parts](https://drafts.csswg.org/css-shadow-parts/).
+    * Instead, replace CSS mixin usage with one of these natively supported
+      alternatives:
+        * CSS Shadow Parts or CSS variables for styling of DOM nodes residing in
+          the Shadow DOM of a child node.
+        * Plain CSS classes, for grouping a set of styles together for easy
+          reuse.
 
 ### Color
 
@@ -451,15 +460,10 @@ function isWindows() {
 ```
 
 `<include src="[path]">` reads the file at `path` and replaces the `<include>`
-tag with the file contents of `[path]`.
-
-Don't use `</include>` to close these tags; they're not needed nor supported.
-
-<div class="note">
-Using <code>&lt;include&gt;</code> simply pastes the entire contents of a file,
-which can lead to duplication.  If you simply want to ensure some code is loaded
-(and usually you do), you should use HTML Imports instead.
-</div>
+tag with the file contents of `[path]`. Don't use `<include>` in new JS code;
+[it is being removed.](https://docs.google.com/document/d/1Z18WTNv28z5FW3smNEm_GtsfVD2IL-CmmAikwjw3ryo/edit?usp=sharing#heading=h.66ycuu6hfi9n)
+Instead, use JS imports in new pages and pages that use JS modules. Use HTML
+imports in existing pages that are still using HTML imports/Polymer 2.
 
 Grit can read and inline resources when enabled via `flattenhtml="true"`.