Fix lifecycle-vs-threads of GpuVDAContext3D.

content/renderer/render_thread_impl.h

Index: content/renderer/render_thread_impl.h
diff --git a/content/renderer/render_thread_impl.h b/content/renderer/render_thread_impl.h
index 5ffdda184c02ec26dee41f10d9817c7e46796466..3849519eb139dfc34997a528029b694a228da41a 100644
--- a/content/renderer/render_thread_impl.h
+++ b/content/renderer/render_thread_impl.h
@@ -218,9 +218,12 @@ class CONTENT_EXPORT RenderThreadImpl : public content::RenderThread,
   // Returns a graphics context shared among all
   // RendererGpuVideoDecoderFactories, or NULL on error.  Context remains owned
   // by this class and must be null-tested before each use to detect context
-  // loss.  The returned WeakPtr<> is only valid on the compositor thread when
+  // loss.  The returned context is only valid on the compositor thread when
   // threaded compositing is enabled.
-  base::WeakPtr<WebGraphicsContext3DCommandBufferImpl> GetGpuVDAContext3D();
+  WebGraphicsContext3DCommandBufferImpl* GetGpuVDAContext3D();
+
+  // Handle loss of the shared GpuVDAContext3D context above.
+  static void OnGpuVDAContextLoss();
 
   // AudioRendererMixerManager instance which manages renderer side mixer
   // instances shared based on configured audio parameters.  Lazily created on