Rewire Android WebView's compositor changed signal.

android_webview/browser/child_frame.h

 // Copyright 2015 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 ANDROID_WEBVIEW_BROWSER_CHILD_FRAME_H_
 #define ANDROID_WEBVIEW_BROWSER_CHILD_FRAME_H_
 
 #include <memory>
 
+#include "android_webview/browser/compositor_id.h"
 #include "base/macros.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/transform.h"
 
 namespace cc {
 class CompositorFrame;
 }
 
 namespace android_webview {
 
 class ChildFrame {
  public:
   ChildFrame(uint32_t output_surface_id,
              std::unique_ptr<cc::CompositorFrame> frame,
-             uint32_t compositor_id,
+             const CompositorID& compositor_id,
              bool viewport_rect_for_tile_priority_empty,
              const gfx::Transform& transform_for_tile_priority,
              bool offscreen_pre_raster,
              bool is_layer);
   ~ChildFrame();
 
   const uint32_t output_surface_id;
   std::unique_ptr<cc::CompositorFrame> frame;
   // The id of the compositor this |frame| comes from.
-  const uint32_t compositor_id;
+  const CompositorID compositor_id;
   const bool viewport_rect_for_tile_priority_empty;
   const gfx::Transform transform_for_tile_priority;
   const bool offscreen_pre_raster;
   const bool is_layer;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ChildFrame);
 };
 
 }  // namespace webview
 
 #endif  // ANDROID_WEBVIEW_BROWSER_CHILD_FRAME_H_