Make reftests work for sky.

sky/viewer/document_view.h

Index: sky/viewer/document_view.h
diff --git a/sky/viewer/document_view.h b/sky/viewer/document_view.h
index b580c5f49cb0e22a7e65c531db0997fd11161ac9..adaeeac7927044a59e3cdf065a2ab5728c702e3c 100644
--- a/sky/viewer/document_view.h
+++ b/sky/viewer/document_view.h
@@ -49,7 +49,8 @@ class DocumentView : public blink::ServiceProvider,
  public:
   DocumentView(mojo::ServiceProviderPtr provider,
                mojo::URLResponsePtr response,
-               mojo::Shell* shell);
+               mojo::Shell* shell,
+               bool is_testing);
   virtual ~DocumentView();
 
   base::WeakPtr<DocumentView> GetWeakPtr();
@@ -70,6 +71,8 @@ class DocumentView : public blink::ServiceProvider,
 
   void StartDebuggerInspectorBackend();
 
+  std::string GetPixelsForTesting();
+
  private:
   // WebWidgetClient methods:
   void initializeLayerTreeView() override;
@@ -129,9 +132,10 @@ class DocumentView : public blink::ServiceProvider,
   scoped_ptr<ScriptRunner> script_runner_;
   scoped_ptr<InspectorHostImpl> inspector_host_;
   scoped_ptr<inspector::InspectorBackendMojo> inspector_backend_;
+  base::WeakPtrFactory<DocumentView> weak_factory_;
   int debugger_id_;
+  bool is_testing_;
 
-  base::WeakPtrFactory<DocumentView> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(DocumentView);
 };