Rewire Android WebView's compositor changed signal.

android_webview/browser/child_frame.h

Index: android_webview/browser/child_frame.h
diff --git a/android_webview/browser/child_frame.h b/android_webview/browser/child_frame.h
index 68c4bd5bb278a4b51e8f215671128afab63f88d9..2cc3a4640e34a40ad3554b6cfbce90e65f662cf8 100644
--- a/android_webview/browser/child_frame.h
+++ b/android_webview/browser/child_frame.h
@@ -7,6 +7,7 @@
 
 #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"
@@ -22,7 +23,7 @@ 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,
@@ -32,7 +33,7 @@ class 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;