[cc] Make LayerImpls point at LayerTreeImpl instead of LTHI

cc/scrollbar_layer_impl.h

Index: cc/scrollbar_layer_impl.h
diff --git a/cc/scrollbar_layer_impl.h b/cc/scrollbar_layer_impl.h
index a35ae3b28cd2b3e3b588181fc2bc9e1b9e9a436d..57e07a748ec1ebaf5d77f9f2b85f32d8ba5922c4 100644
--- a/cc/scrollbar_layer_impl.h
+++ b/cc/scrollbar_layer_impl.h
@@ -18,7 +18,7 @@ class ScrollView;
 
 class CC_EXPORT ScrollbarLayerImpl : public LayerImpl {
 public:
-    static scoped_ptr<ScrollbarLayerImpl> create(LayerTreeHostImpl* hostImpl, int id);
+    static scoped_ptr<ScrollbarLayerImpl> create(LayerTreeImpl* treeImpl, int id);
     virtual ~ScrollbarLayerImpl();
 
     ScrollbarGeometryFixedThumb* scrollbarGeometry() const { return m_geometry.get(); }
@@ -45,7 +45,7 @@ public:
     virtual void didLoseOutputSurface() OVERRIDE;
 
 protected:
-    ScrollbarLayerImpl(LayerTreeHostImpl* hostImpl, int id);
+    ScrollbarLayerImpl(LayerTreeImpl* treeImpl, int id);
 
 private:
     // nested class only to avoid namespace problem