Implement offscreenCanvas.getContext('webgl') on a worker thread

content/renderer/webgraphicscontext3d_provider_impl.h

Index: content/renderer/webgraphicscontext3d_provider_impl.h
diff --git a/content/renderer/webgraphicscontext3d_provider_impl.h b/content/renderer/webgraphicscontext3d_provider_impl.h
index b6358aebb70fdaf85e722268f99087c036bdf8aa..6196b24ba4133b201c253a5f3812e0e36a49ed67 100644
--- a/content/renderer/webgraphicscontext3d_provider_impl.h
+++ b/content/renderer/webgraphicscontext3d_provider_impl.h
@@ -38,6 +38,8 @@ class CONTENT_EXPORT WebGraphicsContext3DProviderImpl
     return provider_.get();
   }
 
+  bool bindToCurrentThread() override;
+
  private:
   scoped_refptr<ContextProviderCommandBuffer> provider_;
 };