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diff --git a/chromium/services/ui/ws2/ids.h b/chromium/services/ui/ws2/ids.h
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+++ b/chromium/services/ui/ws2/ids.h
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+// Copyright 2014 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 SERVICES_UI_WS2_IDS_H_
+#define SERVICES_UI_WS2_IDS_H_
+
+#include <stdint.h>
+
+#include <string>
+#include <tuple>
+
+#include "base/containers/hash_tables.h"
+#include "base/hash.h"
+#include "base/strings/stringprintf.h"
+#include "components/viz/common/surfaces/frame_sink_id.h"
+#include "services/ui/common/types.h"
+#include "services/ui/common/util.h"
+
+namespace ui {
+namespace ws {
+
+// A client id used to indicate no client. That is, no WindowTree ever gets this
+// id.
+const ClientSpecificId kInvalidClientId = 0;
+
+const Id kInvalidTransportId = 0;
+
+// A client id used to indicate WindowServer.
+const ClientSpecificId kWindowServerClientId = 1;
+
+// Every window has a unique id associated with it (WindowId). The id is a
+// combination of the id assigned to the client (the high order bits) and
+// a unique id for the window. Each client (WindowTree) refers to the window
+// by an id assigned by the client (ClientWindowId). To facilitate this
+// WindowTree maintains a mapping between WindowId and ClientWindowId.
+//
+// This model works when the client initiates creation of windows, which is
+// the typical use case. Embed roots and the WindowManager are special, they
+// get access to windows created by other clients. These clients see the
+// id assigned on the server. Such clients have to take care that they only
+// create windows using their client id. To do otherwise could result in
+// multiple windows having the same ClientWindowId. WindowTree enforces
+// that embed roots use the client id in creating the window id to avoid
+// possible conflicts.
+
+// Used for ids assigned by the client.
+using ClientWindowId = viz::FrameSinkId;
+
+struct WindowId {
+  constexpr WindowId(ClientSpecificId client_id, ClientSpecificId window_id)
+      : client_id(client_id), window_id(window_id) {}
+  constexpr WindowId() : client_id(0), window_id(0) {}
+
+  bool operator==(const WindowId& other) const {
+    return other.client_id == client_id && other.window_id == window_id;
+  }
+
+  bool operator!=(const WindowId& other) const { return !(*this == other); }
+
+  bool operator<(const WindowId& other) const {
+    return std::tie(client_id, window_id) <
+           std::tie(other.client_id, other.window_id);
+  }
+
+  std::string ToString() const {
+    return base::StringPrintf("%u:%u", client_id, window_id);
+  }
+
+  ClientSpecificId client_id;
+  ClientSpecificId window_id;
+};
+
+inline WindowId WindowIdFromTransportId(Id id) {
+  return WindowId(HiWord(id), LoWord(id));
+}
+
+// Returns a WindowId that is reserved to indicate no window. That is, no window
+// will ever be created with this id.
+inline WindowId InvalidWindowId() {
+  return WindowId(kInvalidClientId, 0);
+}
+
+// Returns a root window id with a given index offset.
+inline WindowId RootWindowId(uint16_t index) {
+  return WindowId(kWindowServerClientId, 2 + index);
+}
+
+using ClientWindowIdHash = viz::FrameSinkIdHash;
+
+struct WindowIdHash {
+  size_t operator()(const WindowId& id) const {
+    return (id.client_id << 16) | id.window_id;
+  }
+};
+
+}  // namespace ws
+}  // namespace ui
+
+#endif  // SERVICES_UI_WS2_IDS_H_