Use ContextProvider subclass to provide WGC3D pointers

content/renderer/android/synchronous_compositor_factory.h

Index: content/renderer/android/synchronous_compositor_factory.h
diff --git a/content/renderer/android/synchronous_compositor_factory.h b/content/renderer/android/synchronous_compositor_factory.h
index 77c0500426626ed65f50539f53884e31b794893c..f0918307a84a226cc21e8c1b5d756a2b227c3580 100644
--- a/content/renderer/android/synchronous_compositor_factory.h
+++ b/content/renderer/android/synchronous_compositor_factory.h
@@ -19,6 +19,7 @@ class OutputSurface;
 
 namespace content {
 
+class ContextProviderWebContext;
 class InputHandlerManagerClient;
 class StreamTextureFactory;
 
@@ -41,7 +42,7 @@ class SynchronousCompositorFactory {
   // The factory maintains ownership of the returned interface.
   virtual InputHandlerManagerClient* GetInputHandlerManagerClient() = 0;
 
-  virtual scoped_refptr<cc::ContextProvider>
+  virtual scoped_refptr<ContextProviderWebContext>
       GetOffscreenContextProviderForMainThread() = 0;
   virtual scoped_refptr<cc::ContextProvider>
       GetOffscreenContextProviderForCompositorThread() = 0;