cc: Setup API to release OutputSurface from LTHClient.

cc/test/fake_proxy.cc

Index: cc/test/fake_proxy.cc
diff --git a/cc/test/fake_proxy.cc b/cc/test/fake_proxy.cc
index e37e144cb53fef70fb62df48dceaf6080b7cf532..87bea06ce0747e032240ba0a8895c9c70f48ec90 100644
--- a/cc/test/fake_proxy.cc
+++ b/cc/test/fake_proxy.cc
@@ -24,6 +24,10 @@ RendererCapabilities& FakeProxy::GetRendererCapabilities() {
   return capabilities_;
 }
 
+scoped_ptr<OutputSurface> FakeProxy::ReleaseOutputSurface() {
+  return nullptr;
+}
+
 bool FakeProxy::BeginMainFrameRequested() const { return false; }
 
 bool FakeProxy::CommitRequested() const { return false; }