Make browser GPU channel creation async.

ui/compositor/test/in_process_context_factory.h

Index: ui/compositor/test/in_process_context_factory.h
diff --git a/ui/compositor/test/in_process_context_factory.h b/ui/compositor/test/in_process_context_factory.h
index 4e5b3e89e902b2bb79627a72977567e56c8507ef..c8f2d9a693ed3bc8ecfcf1f54c1353193e4c5f73 100644
--- a/ui/compositor/test/in_process_context_factory.h
+++ b/ui/compositor/test/in_process_context_factory.h
@@ -27,9 +27,8 @@ class InProcessContextFactory : public ContextFactory {
   ~InProcessContextFactory() override;
 
   // ContextFactory implementation
-  scoped_ptr<cc::OutputSurface> CreateOutputSurface(
-      Compositor* compositor,
-      bool software_fallback) override;
+  void CreateOutputSurface(base::WeakPtr<Compositor> compositor,
+                           bool software_fallback) override;
 
   scoped_refptr<Reflector> CreateReflector(Compositor* mirrored_compositor,
                                            Layer* mirroring_layer) override;