[cc] Make LayerImpls point at LayerTreeImpl instead of LTHI

cc/scrollbar_layer_impl.cc

Index: cc/scrollbar_layer_impl.cc
diff --git a/cc/scrollbar_layer_impl.cc b/cc/scrollbar_layer_impl.cc
index db9fb4fe6fff8863d847952560b18f1d38925c42..abe7d32f53208df4fa4de6f8b556c96df755ea7d 100644
--- a/cc/scrollbar_layer_impl.cc
+++ b/cc/scrollbar_layer_impl.cc
@@ -14,13 +14,13 @@ using WebKit::WebScrollbar;
 
 namespace cc {
 
-scoped_ptr<ScrollbarLayerImpl> ScrollbarLayerImpl::create(LayerTreeHostImpl* hostImpl, int id)
+scoped_ptr<ScrollbarLayerImpl> ScrollbarLayerImpl::create(LayerTreeImpl* treeImpl, int id)
 {
-    return make_scoped_ptr(new ScrollbarLayerImpl(hostImpl, id));
+    return make_scoped_ptr(new ScrollbarLayerImpl(treeImpl, id));
 }
 
-ScrollbarLayerImpl::ScrollbarLayerImpl(LayerTreeHostImpl* hostImpl, int id)
-    : LayerImpl(hostImpl, id)
+ScrollbarLayerImpl::ScrollbarLayerImpl(LayerTreeImpl* treeImpl, int id)
+    : LayerImpl(treeImpl, id)
     , m_scrollbar(this)
     , m_backTrackResourceId(0)
     , m_foreTrackResourceId(0)