Expose VSync pausing through WindowAndroid and pause VSync during webVR presentation

ui/android/window_android.cc

Index: ui/android/window_android.cc
diff --git a/ui/android/window_android.cc b/ui/android/window_android.cc
index 8a0c8c368ff47df37ddff87326fe0b8819359655..7d4058041ed4bf3552329f51ec38da4726f09d23 100644
--- a/ui/android/window_android.cc
+++ b/ui/android/window_android.cc
@@ -43,6 +43,7 @@ class WindowAndroid::WindowBeginFrameSource : public cc::BeginFrameSource {
   bool IsThrottled() const override { return true; }
 
   void OnVSync(base::TimeTicks frame_time, base::TimeDelta vsync_period);
+  void OnPauseChanged(bool paused);
 
  private:
   WindowAndroid* const window_;
@@ -108,6 +109,11 @@ void WindowAndroid::WindowBeginFrameSource::OnVSync(
     obs.OnBeginFrame(last_begin_frame_args_);
 }
 
+void WindowAndroid::WindowBeginFrameSource::OnPauseChanged(bool paused) {
+  for (auto& obs : observers_)
+    obs.OnBeginFrameSourcePausedChanged(paused);
+}
+
 WindowAndroid::WindowAndroid(JNIEnv* env, jobject obj, int display_id)
     : display_id_(display_id),
       compositor_(NULL),
@@ -244,6 +250,12 @@ void WindowAndroid::OnActivityStarted(JNIEnv* env,
     observer.OnActivityStarted();
 }
 
+void WindowAndroid::SetVSyncPaused(JNIEnv* env,
+                                   const JavaParamRef<jobject>& obj,
+                                   bool paused) {
+  begin_frame_source_->OnPauseChanged(paused);
+}
+
 bool WindowAndroid::HasPermission(const std::string& permission) {
   JNIEnv* env = AttachCurrentThread();
   return Java_WindowAndroid_hasPermission(