Implement one-page-at-a-time mousewheel scrolling in the impl thread.

cc/layer_tree_host_impl.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_LAYER_TREE_HOST_IMPL_H_
 #define CC_LAYER_TREE_HOST_IMPL_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time.h"
@@ skipping 53 matching lines @@
                                     public OutputSurfaceClient,
                                     public TopControlsManagerClient {
     typedef std::vector<LayerImpl*> LayerList;
 
 public:
     static scoped_ptr<LayerTreeHostImpl> create(const LayerTreeSettings&, LayerTreeHostImplClient*, Proxy*);
     virtual ~LayerTreeHostImpl();
 
     // InputHandlerClient implementation
     virtual InputHandlerClient::ScrollStatus scrollBegin(gfx::Point, InputHandlerClient::ScrollInputType) OVERRIDE;
-    virtual bool scrollBy(const gfx::Point&, const gfx::Vector2d&) OVERRIDE;
+    virtual bool scrollBy(const gfx::Point&, const gfx::Vector2d&, bool) OVERRIDE;
     virtual void scrollEnd() OVERRIDE;
     virtual void pinchGestureBegin() OVERRIDE;
     virtual void pinchGestureUpdate(float, gfx::Point) OVERRIDE;
     virtual void pinchGestureEnd() OVERRIDE;
     virtual void startPageScaleAnimation(gfx::Vector2d targetOffset, bool anchorPoint, float pageScale, base::TimeTicks startTime, base::TimeDelta duration) OVERRIDE;
     virtual void scheduleAnimation() OVERRIDE;
     virtual bool haveTouchEventHandlersAt(const gfx::Point&) OVERRIDE;
 
     // TopControlsManagerClient implementation.
     virtual LayerTreeImpl* activeTree() OVERRIDE;
@@ skipping 262 matching lines @@
     size_t m_lastSentMemoryUseBytes;
 
     scoped_ptr<AnimationRegistrar> m_animationRegistrar;
 
     DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYER_TREE_HOST_IMPL_H_