Refactor cc scrollbar layers to separate solid-color vs desktop.

cc/trees/tree_synchronizer.cc

Index: cc/trees/tree_synchronizer.cc
diff --git a/cc/trees/tree_synchronizer.cc b/cc/trees/tree_synchronizer.cc
index 9c4461d9cb0dd2ade6fb9f84a80bbeeb7768f344..f74ff32d331defa9bedd47341085fe815610e999 100644
--- a/cc/trees/tree_synchronizer.cc
+++ b/cc/trees/tree_synchronizer.cc
@@ -11,8 +11,8 @@
 #include "cc/input/scrollbar.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_impl.h"
-#include "cc/layers/scrollbar_layer.h"
-#include "cc/layers/scrollbar_layer_impl.h"
+#include "cc/layers/scrollbar_layer_base.h"
+#include "cc/layers/scrollbar_layer_impl_base.h"
 
 namespace cc {
 
@@ -149,15 +149,16 @@ void UpdateScrollbarLayerPointersRecursiveInternal(
         LayerType, ScrollbarLayerType>(new_layers, layer->child_at(i));
   }
 
-  ScrollbarLayerType* scrollbar_layer = layer->ToScrollbarLayer();
+  ScrollbarLayerType* scrollbar_layer = layer->ToScrollbarLayerBase();
   if (!scrollbar_layer)
     return;
 
   RawPtrLayerImplMap::const_iterator iter =
-      new_layers->find(scrollbar_layer->id());
-  ScrollbarLayerImpl* scrollbar_layer_impl =
-      iter != new_layers->end() ? static_cast<ScrollbarLayerImpl*>(iter->second)
-                               : NULL;
+      new_layers->find(layer->id());
+  ScrollbarLayerImplBase* scrollbar_layer_impl =
+      iter != new_layers->end()
+          ? static_cast<ScrollbarLayerImplBase*>(iter->second)
+          : NULL;
   iter = new_layers->find(scrollbar_layer->scroll_layer_id());
   LayerImpl* scroll_layer_impl =
       iter != new_layers->end() ? iter->second : NULL;
@@ -173,14 +174,15 @@ void UpdateScrollbarLayerPointersRecursiveInternal(
 
 void UpdateScrollbarLayerPointersRecursive(const RawPtrLayerImplMap* new_layers,
                                            Layer* layer) {
-  UpdateScrollbarLayerPointersRecursiveInternal<Layer, ScrollbarLayer>(
+  UpdateScrollbarLayerPointersRecursiveInternal<Layer, ScrollbarLayerBase>(
       new_layers, layer);
 }
 
 void UpdateScrollbarLayerPointersRecursive(const RawPtrLayerImplMap* new_layers,
                                            LayerImpl* layer) {
-  UpdateScrollbarLayerPointersRecursiveInternal<LayerImpl, ScrollbarLayerImpl>(
-      new_layers, layer);
+  UpdateScrollbarLayerPointersRecursiveInternal<
+      LayerImpl,
+      ScrollbarLayerImplBase>(new_layers, layer);
 }
 
 template <typename LayerType>