Update from https://crrev.com/316786

cc/test/test_context_provider.h

Index: cc/test/test_context_provider.h
diff --git a/cc/test/test_context_provider.h b/cc/test/test_context_provider.h
index 3be8b4365b6278e15ecb413ef6660f4b459058ce..9dd7b62a1c3a8244804a327effd117191b7548e8 100644
--- a/cc/test/test_context_provider.h
+++ b/cc/test/test_context_provider.h
@@ -29,10 +29,13 @@ class TestContextProvider : public ContextProvider {
       scoped_ptr<TestWebGraphicsContext3D> context);
 
   bool BindToCurrentThread() override;
+  void DetachFromThread() override;
   Capabilities ContextCapabilities() override;
   gpu::gles2::GLES2Interface* ContextGL() override;
   gpu::ContextSupport* ContextSupport() override;
   class GrContext* GrContext() override;
+  void SetupLock() override;
+  base::Lock* GetLock() override;
   bool IsContextLost() override;
   void VerifyContexts() override;
   void DeleteCachedResources() override;
@@ -74,6 +77,8 @@ class TestContextProvider : public ContextProvider {
   base::Lock destroyed_lock_;
   bool destroyed_;
 
+  base::Lock context_lock_;
+
   LostContextCallback lost_context_callback_;
   MemoryPolicyChangedCallback memory_policy_changed_callback_;
   skia::RefPtr<class GrContext> gr_context_;