Route Scroll events through a cc::InputHandler

ui/views/controls/scrollbar/scroll_bar.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 UI_VIEWS_CONTROLS_SCROLLBAR_SCROLL_BAR_H_
 #define UI_VIEWS_CONTROLS_SCROLLBAR_SCROLL_BAR_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "ui/views/view.h"
@@ skipping 25 matching lines @@
   // requested. The page scroll amount typically corresponds to the
   // visual size of the view. If is_page is false, the 'line scroll' amount
   // is being requested. The line scroll amount typically corresponds to the
   // size of one row/column.
   //
   // The return value should always be positive. A value <= 0 results in
   // scrolling by a fixed amount.
   virtual int GetScrollIncrement(ScrollBar* source,
                                  bool is_page,
                                  bool is_positive) = 0;
+
+  // Invoked by the scroll bar when it receives a ui::ScrollEvent. Typically
+  // these should be treated the same as events received over the viewport.
+  virtual void OnScrollEventFromScrollBar(ui::ScrollEvent* event) = 0;
 };
 
 /////////////////////////////////////////////////////////////////////////////
 //
 // ScrollBar
 //
 // A View subclass to wrap to implement a ScrollBar. Our current windows
 // version simply wraps a native windows scrollbar.
 //
 // A scrollbar is either horizontal or vertical
@@ skipping 51 matching lines @@
   ScrollBarController* controller_;
 
   int max_pos_;
 
   DISALLOW_COPY_AND_ASSIGN(ScrollBar);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_SCROLLBAR_SCROLL_BAR_H_