Follow on for gesture events generated by wheel events.

content/browser/renderer_host/overscroll_controller.h

 // Copyright (c) 2012 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_OVERSCROLL_CONTROLLER_H_
 #define CONTENT_BROWSER_RENDERER_HOST_OVERSCROLL_CONTROLLER_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
@@ skipping 74 matching lines @@
   bool DispatchEventResetsState(const blink::WebInputEvent& event) const;
 
   // Processes an event to update the internal state for overscroll. Returns
   // true if the state is updated, false otherwise.
   bool ProcessEventForOverscroll(const blink::WebInputEvent& event);
 
   // Processes horizontal overscroll. This can update both the overscroll mode
   // and the over scroll amount (i.e. |overscroll_mode_|, |overscroll_delta_x_|
   // and |overscroll_delta_y_|). Returns true if overscroll was handled by the
   // delegate.
-  bool ProcessOverscroll(float delta_x,
-                         float delta_y,
-                         blink::WebInputEvent::Type event_type);
+  bool ProcessOverscroll(float delta_x, float delta_y, bool is_touchpad);

[tdresser, 2016/02/18 14:35:21]

I slightly prefer sending the type here, as it makes the meaning of the
parameter more clear from the call site.

What's the advantage of this approach?

[dtapuska, 2016/02/18 14:41:17]

ProcessOverscroll is called both from MouseWheel and GestureScroll..

I could keep it; but I'd need to move the check if event_type == MouseWheel ||
event_type == GestureScroll && !IsGestureEventFromTouchscreen() inside.

This felt cleaner; but I can change.

 
   // Completes the desired action from the current gesture.
   void CompleteAction();
 
   // Sets the overscroll mode (and triggers callback in the delegate when
   // appropriate).
   void SetOverscrollMode(OverscrollMode new_mode);
 
   // The current state of overscroll gesture.
   OverscrollMode overscroll_mode_;
 
   // Used to keep track of the scrolling state.
   // If scrolling starts, and some scroll events are consumed at the beginning
   // of the scroll (i.e. some content on the web-page was scrolled), then do not
   // process any of the subsequent scroll events for generating overscroll
   // gestures.
   ScrollState scroll_state_;
 
   // The amount of overscroll in progress. These values are invalid when
   // |overscroll_mode_| is set to OVERSCROLL_NONE.
   float overscroll_delta_x_;
   float overscroll_delta_y_;
 
   // The delegate that receives the overscroll updates. The delegate is not
   // owned by this controller.
   OverscrollControllerDelegate* delegate_;
+  bool use_gesutre_wheel_scrolling_;
 
   DISALLOW_COPY_AND_ASSIGN(OverscrollController);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_OVERSCROLL_CONTROLLER_H_