cc: Implement shared worker contexts. (v1)

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index 285ca7f68e4847b0a02ed4ef02767444c6537b33..90e394b429663b23a9f8571e3fbb4616e6faaabe 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -1022,10 +1022,15 @@ scoped_ptr<cc::OutputSurface> RenderWidget::CreateOutputSurface(bool fallback) {
 
     worker_context_provider = ContextProviderCommandBuffer::Create(
         CreateGraphicsContext3D(false), RENDER_WORKER_CONTEXT);
-    if (!worker_context_provider.get()) {
+    if (!worker_context_provider.get() ||
+        !worker_context_provider->BindToCurrentThread()) {
       // Cause the compositor to wait and try again.
       return scoped_ptr<cc::OutputSurface>();
     }
+    worker_context_provider->SetupLock();
+    // Detach from thread to allow context to be destroyed on a different
+    // thread without being used.
+    worker_context_provider->DetachFromThread();
   }
 
   uint32 output_surface_id = next_output_surface_id_++;