Defer compositor context creation to the thread.

cc/output/output_surface.h

Index: cc/output/output_surface.h
diff --git a/cc/output/output_surface.h b/cc/output/output_surface.h
index 326b2fd2fbf22e8f3ff832b208c4a316c744a583..e1baa650f0513691495069c33cec8cdd47cba43e 100644
--- a/cc/output/output_surface.h
+++ b/cc/output/output_surface.h
@@ -46,17 +46,21 @@ class OutputSurfaceClient;
 //      surface (on the compositor thread) and go back to step 1.
 class CC_EXPORT OutputSurface : public base::trace_event::MemoryDumpProvider {
  public:
-  OutputSurface(scoped_refptr<ContextProvider> context_provider,
-                scoped_refptr<ContextProvider> worker_context_provider,
-                scoped_refptr<VulkanContextProvider> vulkan_context_provider,
-                std::unique_ptr<SoftwareOutputDevice> software_device);
-  OutputSurface(scoped_refptr<ContextProvider> context_provider,
-                scoped_refptr<ContextProvider> worker_context_provider);
-  explicit OutputSurface(scoped_refptr<ContextProvider> context_provider);
+  OutputSurface(
+      std::unique_ptr<ContextProvider::DeferredCreate> context_provider_create,
+      scoped_refptr<ContextProvider> worker_context_provider,

[piman, 2016/05/17 03:41:40]

Is the intent that the worker will also come from a
ContextProvider::DeferredCreate?

[danakj, 2016/05/17 19:53:33]

Yes. I did the compositor one first since it's already bound on the compositor
thread. The worker patch will look similar but requires the weak reference on
the main thread to reuse, so it's a bit more complicated. So this is easier
first while we sort out the design.

+      scoped_refptr<VulkanContextProvider> vulkan_context_provider,
+      std::unique_ptr<SoftwareOutputDevice> software_device);
+  OutputSurface(
+      std::unique_ptr<ContextProvider::DeferredCreate> context_provider_create,
+      scoped_refptr<ContextProvider> worker_context_provider);
+  explicit OutputSurface(
+      std::unique_ptr<ContextProvider::DeferredCreate> context_provider_create);
   explicit OutputSurface(std::unique_ptr<SoftwareOutputDevice> software_device);
 
-  OutputSurface(scoped_refptr<ContextProvider> context_provider,
-                std::unique_ptr<SoftwareOutputDevice> software_device);
+  OutputSurface(
+      std::unique_ptr<ContextProvider::DeferredCreate> context_provider_create,
+      std::unique_ptr<SoftwareOutputDevice> software_device);
 
   ~OutputSurface() override;
 
@@ -177,6 +181,7 @@ class CC_EXPORT OutputSurface : public base::trace_event::MemoryDumpProvider {
   void PostSwapBuffersComplete();
 
   struct OutputSurface::Capabilities capabilities_;
+  std::unique_ptr<ContextProvider::DeferredCreate> context_provider_create_;
   scoped_refptr<ContextProvider> context_provider_;
   scoped_refptr<ContextProvider> worker_context_provider_;
   scoped_refptr<VulkanContextProvider> vulkan_context_provider_;