Find root scroll layer at tree activation

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 67 matching lines @@
     virtual bool scrollBy(const gfx::Point&, const gfx::Vector2d&) 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;
     virtual void setNeedsUpdateDrawProperties() OVERRIDE;
     virtual void setNeedsRedraw() OVERRIDE;
+    virtual bool haveRootScrollLayer() const OVERRIDE;
+    virtual float rootScrollLayerTotalScrollY() const OVERRIDE;
 
     struct CC_EXPORT FrameData : public RenderPassSink {
         FrameData();
         ~FrameData();
 
         std::vector<gfx::Rect> occludingScreenSpaceRects;
         std::vector<gfx::Rect> nonOccludingScreenSpaceRects;
         RenderPassList renderPasses;
         RenderPassIdHashMap renderPassesById;
         const LayerList* renderSurfaceLayerList;
@@ skipping 55 matching lines @@
     bool initializeRenderer(scoped_ptr<OutputSurface>);
     bool isContextLost();
     TileManager* tileManager() { return m_tileManager.get(); }
     Renderer* renderer() { return m_renderer.get(); }
     const RendererCapabilities& rendererCapabilities() const;
 
     bool swapBuffers();
 
     void readback(void* pixels, const gfx::Rect&);
 
+    LayerTreeImpl* activeTree() { return m_activeTree.get(); }
     const LayerTreeImpl* activeTree() const { return m_activeTree.get(); }
     LayerTreeImpl* pendingTree() { return m_pendingTree.get(); }
     const LayerTreeImpl* pendingTree() const { return m_pendingTree.get(); }
     void createPendingTree();
     void checkForCompletedTextures();
     virtual void activatePendingTreeIfNeeded();
 
     // Shortcuts to layers on the active tree.
     LayerImpl* rootLayer() const;
     LayerImpl* rootScrollLayer() const;
@@ skipping 176 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_