Send touch cancel to renderer when scrolling starts

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 34 matching lines @@
   // single touch-move event). The event may also be immediately forwarded to
   // the renderer (e.g. when there are no other queued touch event).
   void QueueEvent(const TouchEventWithLatencyInfo& event);
 
   // Notifies the queue that a touch-event has been processed by the renderer.
   // At this point, the queue may send one or more gesture events and/or
   // additional queued touch-events to the renderer.
   void ProcessTouchAck(InputEventAckState ack_result,
                        const ui::LatencyInfo& latency_info);
 
+  // When GestureScrollBegin is received, we send a touch cancel to renderer,
+  // route all the following touch events directly to client, and ignore the
+  // ack for the touch cancel. When GestureScrollEnd/GestureFlingStart is
+  // received, we resume the normal flow of sending touch events to renderer.
+  void OnGestureScrollEvent(const GestureEventWithLatencyInfo& gesture_event);
+
   // Empties the queue of touch events. This may result in any number of gesture
   // events being sent to the renderer.
   void FlushQueue();
 
   // Returns whether the event-queue is empty.
   bool empty() const WARN_UNUSED_RESULT {
     return touch_queue_.empty();
   }
 
-  void set_no_touch_move_to_renderer(bool value) {
-    no_touch_move_to_renderer_ = value;
-  }
-
  private:
   friend class MockRenderWidgetHost;
   friend class ImmediateInputRouterTest;
 
   CONTENT_EXPORT size_t GetQueueSize() const;
   CONTENT_EXPORT const TouchEventWithLatencyInfo& GetLatestEvent() const;
 
   // Walks the queue, checking each event for |ShouldForwardToRenderer()|.
   // If true, forwards the touch event and stops processing further events.
   // If false, acks the event with |INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS|.
@@ skipping 10 matching lines @@
   TouchEventQueueClient* client_;
 
   typedef std::deque<CoalescedWebTouchEvent*> TouchQueue;
   TouchQueue touch_queue_;
 
   // Maintain the ACK status for each touch point.
   typedef std::map<int, InputEventAckState> TouchPointAckStates;
   TouchPointAckStates touch_ack_states_;
 
   // Used to defer touch forwarding when ack dispatch triggers |QueueEvent()|.
-  bool dispatching_touch_ack_;
+  // If not NULL, |dispatching_touch_ack_| is the touch event of which the ack
+  // is being dispatched.
+  CoalescedWebTouchEvent* dispatching_touch_ack_;
 
-  // Don't send touch move events to renderer. This is enabled when the page
-  // is scrolling. This behaviour is currently enabled only on aura behind a
-  // flag.
-  bool no_touch_move_to_renderer_;
+  // Don't send touch events to renderer. This is enabled when the page
+  // is scrolling. This behaviour is currently enabled only on aura behind
+  // a flag.
+  bool no_touch_to_renderer_;
 
   DISALLOW_COPY_AND_ASSIGN(TouchEventQueue);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_TOUCH_EVENT_QUEUE_H_