Activate LayerImpl tree with sync+push instead of pointer swap

cc/scrollbar_layer_impl.h

 // Copyright 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 CC_SCROLLBAR_LAYER_IMPL_H_
 #define CC_SCROLLBAR_LAYER_IMPL_H_
 
 #include "cc/cc_export.h"
 #include "cc/scrollbar_geometry_fixed_thumb.h"
 #include "cc/scrollbar_layer_impl_base.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebRect.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebVector.h"
 
 namespace cc {
 
 class ScrollView;
 
 class CC_EXPORT ScrollbarLayerImpl : public ScrollbarLayerImplBase {
 public:
     static scoped_ptr<ScrollbarLayerImpl> create(LayerTreeImpl* treeImpl, int id);
     virtual ~ScrollbarLayerImpl();
 
+    virtual ScrollbarLayerImpl* toScrollbarLayer() OVERRIDE;
+    int scrollLayerId() const { return m_scrollLayerId; }
+    void setScrollLayerId(int id) { m_scrollLayerId = id; }
+
     ScrollbarGeometryFixedThumb* scrollbarGeometry() const { return m_geometry.get(); }
     void setScrollbarGeometry(scoped_ptr<ScrollbarGeometryFixedThumb>);
     void setScrollbarData(WebKit::WebScrollbar*);
 
     void setBackTrackResourceId(ResourceProvider::ResourceId id) { m_backTrackResourceId = id; }
     void setForeTrackResourceId(ResourceProvider::ResourceId id) { m_foreTrackResourceId = id; }
     void setThumbResourceId(ResourceProvider::ResourceId id) { m_thumbResourceId = id; }
 
-    void setOwningLayer(LayerImpl* owningLayer);
 
     // ScrollbarLayerImplBase implementation.
     virtual float currentPos() const OVERRIDE;
     virtual int totalSize() const OVERRIDE;
     virtual int maximum() const OVERRIDE;
 
     void setCurrentPos(float currentPos) { m_currentPos = currentPos; }
     void setTotalSize(int totalSize) { m_totalSize = totalSize; }
     void setMaximum(int maximum) { m_maximum = maximum; }
 
     virtual WebKit::WebScrollbar::Orientation orientation() const OVERRIDE;
 
+    virtual scoped_ptr<LayerImpl> createLayerImpl(LayerTreeImpl*) OVERRIDE;
+    virtual void pushPropertiesTo(LayerImpl*) OVERRIDE;
+
     virtual void appendQuads(QuadSink&, AppendQuadsData&) OVERRIDE;
 
     virtual void didLoseOutputSurface() OVERRIDE;
 
 protected:
     ScrollbarLayerImpl(LayerTreeImpl* treeImpl, int id);
 
 private:
     // nested class only to avoid namespace problem
     class Scrollbar : public WebKit::WebScrollbar {
@@ skipping 32 matching lines @@
     ResourceProvider::ResourceId m_backTrackResourceId;
     ResourceProvider::ResourceId m_foreTrackResourceId;
     ResourceProvider::ResourceId m_thumbResourceId;
 
     scoped_ptr<ScrollbarGeometryFixedThumb> m_geometry;
 
     float m_currentPos;
     int m_totalSize;
     int m_maximum;
 
+    int m_scrollLayerId;
+
     // Data to implement Scrollbar
     WebKit::WebScrollbar::ScrollbarOverlayStyle m_scrollbarOverlayStyle;
     WebKit::WebVector<WebKit::WebRect> m_tickmarks;
     WebKit::WebScrollbar::Orientation m_orientation;
     WebKit::WebScrollbar::ScrollbarControlSize m_controlSize;
     WebKit::WebScrollbar::ScrollbarPart m_pressedPart;
     WebKit::WebScrollbar::ScrollbarPart m_hoveredPart;
 
     bool m_isScrollableAreaActive;
     bool m_isScrollViewScrollbar;
     bool m_enabled;
     bool m_isCustomScrollbar;
     bool m_isOverlayScrollbar;
 };
 
 }
 #endif  // CC_SCROLLBAR_LAYER_IMPL_H_