Make browser GPU channel creation async.

mojo/aura/surface_context_factory.cc

Index: mojo/aura/surface_context_factory.cc
diff --git a/mojo/aura/surface_context_factory.cc b/mojo/aura/surface_context_factory.cc
index aa964012ecd1a011e07313f53da5124d50c4da0f..34cc316a822c82a6857aa672d58e2e58bf5984ae 100644
--- a/mojo/aura/surface_context_factory.cc
+++ b/mojo/aura/surface_context_factory.cc
@@ -20,10 +20,10 @@ SurfaceContextFactory::SurfaceContextFactory(Shell* shell, View* view)
 SurfaceContextFactory::~SurfaceContextFactory() {
 }
 
-scoped_ptr<cc::OutputSurface> SurfaceContextFactory::CreateOutputSurface(
-    ui::Compositor* compositor,
+void SurfaceContextFactory::CreateOutputSurface(
+    base::WeakPtr<ui::Compositor> compositor,
     bool software_fallback) {
-  return surface_binding_.CreateOutputSurface();
+  compositor->SetOutputSurface(surface_binding_.CreateOutputSurface());
 }
 
 scoped_refptr<ui::Reflector> SurfaceContextFactory::CreateReflector(