Implement Wheel Gesture Scrolling on OSX.

content/browser/renderer_host/input/mouse_wheel_event_queue.h

 // Copyright 2016 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_MOUSE_WHEEL_EVENT_QUEUE_H_
 #define CONTENT_BROWSER_RENDERER_HOST_INPUT_MOUSE_WHEEL_EVENT_QUEUE_H_
 
 #include <deque>
 
 #include "base/time/time.h"
@@ skipping 57 matching lines @@
   bool has_pending() const WARN_UNUSED_RESULT {
     return !wheel_queue_.empty() || event_sent_for_gesture_ack_;
   }
 
   size_t queued_size() const { return wheel_queue_.size(); }
   bool event_in_flight() const { return event_sent_for_gesture_ack_; }
 
  private:
   void TryForwardNextEventToRenderer();
   void SendScrollEnd(blink::WebGestureEvent update_event);
-  void SendGesture(const GestureEventWithLatencyInfo& gesture);
+  void SendGesture(const GestureEventWithLatencyInfo& gesture, bool needs_end);
 
   MouseWheelEventQueueClient* client_;
   bool needs_scroll_begin_;
   base::OneShotTimer scroll_end_timer_;
 
   typedef std::deque<QueuedWebMouseWheelEvent*> WheelEventQueue;
   WheelEventQueue wheel_queue_;
   scoped_ptr<QueuedWebMouseWheelEvent> event_sent_for_gesture_ack_;
   bool send_gestures_;
   int64_t scroll_transaction_ms_;
   blink::WebGestureDevice scrolling_device_;
 
   DISALLOW_COPY_AND_ASSIGN(MouseWheelEventQueue);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_MOUSE_WHEEL_EVENT_QUEUE_H_