Implement Wheel Gesture Scrolling on OSX.

content/renderer/input/render_widget_input_handler_delegate.h

 // Copyright 2015 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_RENDERER_INPUT_RENDER_WIDGET_INPUT_HANDLER_DELEGATE_H_
 #define CONTENT_RENDERER_INPUT_RENDER_WIDGET_INPUT_HANDLER_DELEGATE_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "content/common/content_export.h"
 #include "content/common/input/input_event_ack.h"
@@ skipping 31 matching lines @@
   // at the given point.
   virtual bool HasTouchEventHandlersAt(const gfx::Point& point) const = 0;
 
   // Called to forward a mouse wheel event to the compositor thread, to effect
   // the elastic overscroll effect.
   virtual void ObserveWheelEventAndResult(
       const blink::WebMouseWheelEvent& wheel_event,
       const gfx::Vector2dF& wheel_unused_delta,
       bool event_processed) = 0;
 
+  virtual void ObserveGestureEventAndResult(

[Charlie Reis, 2016/03/09 22:49:17]

nit: Add a similar comment as above.

[dtapuska, 2016/03/10 19:51:15]

Done.

+      const blink::WebGestureEvent& gesture_event,
+      const gfx::Vector2dF& unused_delta,
+      bool event_processed) = 0;
+
   // Notifies that a key event was just handled.
   virtual void OnDidHandleKeyEvent() = 0;
 
   // Notifies that an overscroll was completed from Blink.
   virtual void OnDidOverscroll(const DidOverscrollParams& params) = 0;
 
   // Called when an ACK is ready to be sent to the input event provider.
   virtual void OnInputEventAck(scoped_ptr<InputEventAck> input_event_ack) = 0;
 
   // Called when a non-blocking event (DISPATCH_TYPE_NON_BLOCKING) of
@@ skipping 24 matching lines @@
   // won't be sent to WebKit or trigger DidHandleMouseEvent().
   virtual bool WillHandleMouseEvent(const blink::WebMouseEvent& event) = 0;
 
  protected:
   virtual ~RenderWidgetInputHandlerDelegate() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_INPUT_RENDER_WIDGET_INPUT_HANDLER_DELEGATE_H_