Make reftests work for sky.

sky/compositor/layer.h

Index: sky/compositor/layer.h
diff --git a/sky/compositor/layer.h b/sky/compositor/layer.h
index 94925278652b7e33146d2c5dae537b8f741d9438..dc6dba783880bd5319aa40ab6ddbc94946be89c3 100644
--- a/sky/compositor/layer.h
+++ b/sky/compositor/layer.h
@@ -8,6 +8,7 @@
 #include "base/memory/ref_counted.h"
 #include "mojo/gpu/gl_texture.h"
 #include "sky/compositor/layer_client.h"
+#include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace sky {
@@ -15,11 +16,12 @@ class LayerHost;
 
 class Layer : public base::RefCounted<Layer> {
  public:
-  explicit Layer(LayerClient* client);
+  explicit Layer(LayerClient* client, bool is_testing_);
 
   void ClearClient();
 
   void SetSize(const gfx::Size& size);
+  std::string GetPixelsForTesting();
   void Display();
 
   scoped_ptr<mojo::GLTexture> GetTexture();
@@ -35,8 +37,9 @@ class Layer : public base::RefCounted<Layer> {
   LayerClient* client_;
   LayerHost* host_;
   gfx::Size size_;
-
+  SkBitmap bitmap_;
   scoped_ptr<mojo::GLTexture> texture_;
+  bool is_testing_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };