Coalesce async touch move events until the ack back from render

content/browser/renderer_host/input/touch_event_queue.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_INPUT_TOUCH_EVENT_QUEUE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_INPUT_TOUCH_EVENT_QUEUE_H_
 
 #include <deque>
 #include <map>
 
@@ skipping 84 matching lines @@
   bool empty() const WARN_UNUSED_RESULT {
     return touch_queue_.empty();
   }
 
   size_t size() const {
     return touch_queue_.size();
   }
 
   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;
   friend class TouchTimeoutHandler;
   friend class TouchEventQueueTest;
 
   bool HasPendingAsyncTouchMoveForTesting() const;
   bool IsTimeoutRunningForTesting() const;
   const TouchEventWithLatencyInfo& GetLatestEventForTesting() const;
 
@@ skipping 85 matching lines @@
   // and ack'ed immediately, but remain buffered in |pending_async_touchmove_|
   // until a sufficient time period has elapsed since the last sent touch event.
   // For details see the design doc at http://goo.gl/lVyJAa.
   bool send_touch_events_async_;
   scoped_ptr<TouchEventWithLatencyInfo> pending_async_touchmove_;
   double last_sent_touch_timestamp_sec_;
 
   // 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);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_TOUCH_EVENT_QUEUE_H_