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 f307257ff05819fb35b16d65cddf4780cea09f74..e133625313bb69a8c57888da5748af83dc538e00 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();

[enne (OOO), 2013/08/12 23:15:01]

I agree with jamesr that there's really not that much in ScrollbarLayerBase
going on that needs to be shared.

One suggestion would be to have a ScrollbarLayerInterface that exposed
Orientation() and ScrollLayerId() and have both ScrollbarLayer and
SolidColorScrollbarLayer implement that interface.  Then
SolidColorScrollbarLayer would no longer need to inherit from
ContentsScalingLayer, but you wouldn't have to complicate TreeSynchronizer with
different kinds of scrollbars.

[wjmaclean, 2013/08/14 18:19:44]

Sure, that sounds good. I've converted to an interface as you suggest (let me
know if the way I've done this seems reasonable).

   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;
@@ -165,7 +166,7 @@ void UpdateScrollbarLayerPointersRecursiveInternal(
   DCHECK(scrollbar_layer_impl);
   DCHECK(scroll_layer_impl);
 
-  if (scrollbar_layer->Orientation() == HORIZONTAL)
+  if (scrollbar_layer->orientation() == HORIZONTAL)
     scroll_layer_impl->SetHorizontalScrollbarLayer(scrollbar_layer_impl);
   else
     scroll_layer_impl->SetVerticalScrollbarLayer(scrollbar_layer_impl);
@@ -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);
 }
 
 // static