Make reftests work for sky.

sky/viewer/viewer.cc

Index: sky/viewer/viewer.cc
diff --git a/sky/viewer/viewer.cc b/sky/viewer/viewer.cc
index eb5b6d0fba31b3bb14f243cf89fbfd4146359401..26a070f783d8ba0a8a885314abef23afcdc5d53c 100644
--- a/sky/viewer/viewer.cc
+++ b/sky/viewer/viewer.cc
@@ -24,6 +24,9 @@
 
 namespace sky {
 
+// Load the viewer in testing mode so we can dump pixels.
+const char kTesting[] = "--testing";
+
 class Viewer : public mojo::ApplicationDelegate,
                public mojo::InterfaceFactory<mojo::ContentHandler> {
  public:
@@ -34,6 +37,8 @@ class Viewer : public mojo::ApplicationDelegate,
  private:
   // Overridden from ApplicationDelegate:
   virtual void Initialize(mojo::ApplicationImpl* app) override {
+    is_testing_ = app->HasArg(kTesting);
+
     platform_impl_.reset(new PlatformImpl(app));
     blink::initialize(platform_impl_.get());
     base::i18n::InitializeICU();
@@ -50,10 +55,11 @@ class Viewer : public mojo::ApplicationDelegate,
   // Overridden from InterfaceFactory<ContentHandler>
   virtual void Create(mojo::ApplicationConnection* connection,
                       mojo::InterfaceRequest<mojo::ContentHandler> request) override {
-    mojo::BindToRequest(new ContentHandlerImpl(), &request);
+    mojo::BindToRequest(new ContentHandlerImpl(is_testing_), &request);
   }
 
   scoped_ptr<PlatformImpl> platform_impl_;
+  bool is_testing_;
 
   DISALLOW_COPY_AND_ASSIGN(Viewer);
 };