Adding compositor callbacks to RenderWidgetHostViewAndroid

ui/base/android/window_android.h

Index: ui/base/android/window_android.h
diff --git a/ui/base/android/window_android.h b/ui/base/android/window_android.h
index 6c16b45d89c36413e90d05e64ce1bd1de9c301dc..1da707393449cef62a6dac65255d447b2ddab21c 100644
--- a/ui/base/android/window_android.h
+++ b/ui/base/android/window_android.h
@@ -9,11 +9,14 @@
 #include <vector>
 #include "base/android/jni_helper.h"
 #include "base/android/scoped_java_ref.h"
+#include "base/observer_list.h"
 #include "ui/base/ui_export.h"
 #include "ui/gfx/vector2d_f.h"
 
 namespace ui {
 
+class WindowAndroidObserver;
+
 // Android implementation of the activity window.
 class UI_EXPORT WindowAndroid {
  public:
@@ -34,12 +37,23 @@ class UI_EXPORT WindowAndroid {
   bool GrabSnapshot(int content_x, int content_y, int width, int height,
                     std::vector<unsigned char>* png_representation);
 
+  // Compositor callback relay.
+  void OnCompositingDidCommit();
+
+  void AttachCompositor();
+  void DetachCompositor();
+
+  void AddObserver(WindowAndroidObserver* observer);
+  void RemoveObserver(WindowAndroidObserver* observer);
+
  private:
   ~WindowAndroid();
 
   JavaObjectWeakGlobalRef weak_java_window_;
   gfx::Vector2dF content_offset_;
 
+  ObserverList<WindowAndroidObserver> observer_list_;
+
   DISALLOW_COPY_AND_ASSIGN(WindowAndroid);
 };