Coalesce async touch move events until the ack back from render

content/browser/renderer_host/input/touch_event_queue.h

Index: content/browser/renderer_host/input/touch_event_queue.h
diff --git a/content/browser/renderer_host/input/touch_event_queue.h b/content/browser/renderer_host/input/touch_event_queue.h
index a61b90d8eca8c1707d31b3e9bfbadabb175047a0..6fc0a6e63924e466b3ce14da68c27569944bb146 100644
--- a/content/browser/renderer_host/input/touch_event_queue.h
+++ b/content/browser/renderer_host/input/touch_event_queue.h
@@ -102,6 +102,10 @@ class CONTENT_EXPORT TouchEventQueue {
 
   bool has_handlers() const { return has_handlers_; }
 
+  bool IsSendingTouchEventsAsync() const { return send_touch_events_async_; }
+
+  void ReceiveAsyncTouchMoveAck() { receiving_async_touch_move_ack_ = true; }
+
  private:
   class TouchTimeoutHandler;
   class TouchMoveSlopSuppressor;
@@ -207,6 +211,9 @@ class CONTENT_EXPORT TouchEventQueue {
   // Event is saved to compare pointer positions for new touchmove events.
   scoped_ptr<blink::WebTouchEvent> last_sent_touchevent_;
 
+  // Whether received an ACK from render on async touchmove event.
+  bool receiving_async_touch_move_ack_;
+
   DISALLOW_COPY_AND_ASSIGN(TouchEventQueue);
 };