Notify Blink about start of gesture scroll through a queued event.

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 <stddef.h>
 #include <stdint.h>
 
@@ skipping 52 matching lines @@
   TouchEventQueue(TouchEventQueueClient* client, const Config& config);
 
   ~TouchEventQueue();
 
   // Adds an event to the queue. The event may be coalesced with previously
   // queued events (e.g. consecutive touch-move events can be coalesced into a
   // 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);
 
+  // Adds a TouchScrollStarted event to the front of the queue.
+  void PrependTouchScrollNotification();
+
   // Notifies the queue that a touch-event has been processed by the renderer.
   // At this point, if the ack is for async touchmove, remove the uncancelable
   // touchmove from the front of the queue and decide if it should dispatch the
   // next pending async touch move event, otherwise 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,
                        const uint32_t unique_touch_event_id);
 
   // When GestureScrollBegin is received, we send a touch cancel to renderer,
@@ skipping 19 matching lines @@
   void SetAckTimeoutEnabled(bool enabled);
 
   // Sets whether the current site has a mobile friendly viewport. This
   // determines which ack timeout delay will be used for *future* touch events.
   // The default assumption is that the site is *not* mobile-optimized.
   void SetIsMobileOptimizedSite(bool mobile_optimized_site);
 
   // Whether ack timeout behavior is supported and enabled for the current site.
   bool IsAckTimeoutEnabled() const;
 
-  bool IsForwardingTouches();
-
   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_; }
 
@@ skipping 118 matching lines @@
 
   // Event is saved to compare pointer positions for new touchmove events.
   scoped_ptr<blink::WebTouchEvent> last_sent_touchevent_;
 
   DISALLOW_COPY_AND_ASSIGN(TouchEventQueue);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_TOUCH_EVENT_QUEUE_H_