Impl thread smooth scrolling.

cc/input/input_handler.h

 // Copyright 2011 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 CC_INPUT_INPUT_HANDLER_H_
 #define CC_INPUT_INPUT_HANDLER_H_
 
 #include "base/basictypes.h"
 #include "base/time/time.h"
 #include "cc/base/cc_export.h"
@@ skipping 58 matching lines @@
   virtual void BindToClient(InputHandlerClient* client) = 0;
 
   // Selects a layer to be scrolled at a given point in viewport (logical
   // pixel) coordinates. Returns ScrollStarted if the layer at the coordinates
   // can be scrolled, ScrollOnMainThread if the scroll event should instead be
   // delegated to the main thread, or ScrollIgnored if there is nothing to be
   // scrolled at the given coordinates.
   virtual ScrollStatus ScrollBegin(const gfx::Point& viewport_point,
                                    ScrollInputType type) = 0;
 
+  virtual ScrollStatus ScrollAnimated(const gfx::Point& viewport_point,
+                                      const gfx::Vector2dF& scroll_delta) = 0;
+
   // Scroll the selected layer starting at the given position. If the scroll
   // type given to ScrollBegin was a gesture, then the scroll point and delta
   // should be in viewport (logical pixel) coordinates. Otherwise they are in
   // scrolling layer's (logical pixel) space. If there is no room to move the
   // layer in the requested direction, its first ancestor layer that can be
   // scrolled will be moved instead. If no layer can be moved in the requested
   // direction at all, then false is returned. If any layer is moved, then
   // true is returned.
   // If the scroll delta hits the root layer, and the layer can no longer move,
   // the root overscroll accumulated within this ScrollBegin() scope is reported
@@ skipping 56 matching lines @@
   InputHandler() {}
   virtual ~InputHandler() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(InputHandler);
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_INPUT_HANDLER_H_