cc: Introduce BeginFrame sequence numbers and acknowledgements.

ui/android/window_android.h

Index: ui/android/window_android.h
diff --git a/ui/android/window_android.h b/ui/android/window_android.h
index 05279ced4c92a2a9e8827b15c67e0c94187a9e11..9601597171da65f22410cd378b28cc6b66563f7c 100644
--- a/ui/android/window_android.h
+++ b/ui/android/window_android.h
@@ -6,6 +6,7 @@
 #define UI_ANDROID_WINDOW_ANDROID_H_
 
 #include <jni.h>
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -18,6 +19,10 @@
 #include "ui/android/view_android.h"
 #include "ui/gfx/geometry/vector2d_f.h"
 
+namespace cc {
+class BeginFrameSource;
+}
+
 namespace display {
 class DisplayAndroidManager;
 }
@@ -59,8 +64,8 @@ class UI_ANDROID_EXPORT WindowAndroid : public ViewAndroid {
   void RemoveObserver(WindowAndroidObserver* observer);
 
   WindowAndroidCompositor* GetCompositor() { return compositor_; }
+  cc::BeginFrameSource* GetBeginFrameSource();
 
-  void RequestVSyncUpdate();
   void SetNeedsAnimate();
   void Animate(base::TimeTicks begin_frame_time);
   void OnVSync(JNIEnv* env,
@@ -80,6 +85,8 @@ class UI_ANDROID_EXPORT WindowAndroid : public ViewAndroid {
   // Return whether the specified Android permission can be requested by Chrome.
   bool CanRequestPermission(const std::string& permission);
 
+  void OnNeedsBeginFramesChange(bool needs_begin_frames);
+
   static WindowAndroid* CreateForTesting();
   void DestroyForTesting();
 
@@ -88,6 +95,8 @@ class UI_ANDROID_EXPORT WindowAndroid : public ViewAndroid {
 
   ~WindowAndroid() override;
 
+  void RequestVSyncUpdate();
+
   // ViewAndroid overrides.
   WindowAndroid* GetWindowAndroid() const override;
 
@@ -101,6 +110,10 @@ class UI_ANDROID_EXPORT WindowAndroid : public ViewAndroid {
 
   base::ObserverList<WindowAndroidObserver> observer_list_;
 
+  class WindowBeginFrameSource;
+  std::unique_ptr<WindowBeginFrameSource> begin_frame_source_;
+  bool needs_begin_frames_;
+
   DISALLOW_COPY_AND_ASSIGN(WindowAndroid);
 };