Defer compositor context creation to the thread.

cc/test/pixel_test_output_surface.h

Index: cc/test/pixel_test_output_surface.h
diff --git a/cc/test/pixel_test_output_surface.h b/cc/test/pixel_test_output_surface.h
index 6cd4191adedce7b7eb7b77f905198a3188fa6865..fcad42428481aca1be16afa45c4df509f34939d6 100644
--- a/cc/test/pixel_test_output_surface.h
+++ b/cc/test/pixel_test_output_surface.h
@@ -14,12 +14,12 @@ class BeginFrameSource;
 class PixelTestOutputSurface : public OutputSurface {
  public:
   explicit PixelTestOutputSurface(
-      scoped_refptr<ContextProvider> context_provider,
+      std::unique_ptr<ContextProvider::DeferredCreate> context_provider_create,
       scoped_refptr<ContextProvider> worker_context_provider,
       bool flipped_output_surface,
       std::unique_ptr<BeginFrameSource> begin_frame_source);
   explicit PixelTestOutputSurface(
-      scoped_refptr<ContextProvider> context_provider,
+      std::unique_ptr<ContextProvider::DeferredCreate> context_provider_create,
       bool flipped_output_surface,
       std::unique_ptr<BeginFrameSource> begin_frame_source);
   explicit PixelTestOutputSurface(