cc: Setup API to release OutputSurface from LTHClient.

cc/trees/thread_proxy.cc

Index: cc/trees/thread_proxy.cc
diff --git a/cc/trees/thread_proxy.cc b/cc/trees/thread_proxy.cc
index a528e3eb3d1b5c7905a845ce2a7a82218a8ef122..33339119e52f7a3f7f04f938e0649d0262af1ba1 100644
--- a/cc/trees/thread_proxy.cc
+++ b/cc/trees/thread_proxy.cc
@@ -219,6 +219,10 @@ void ThreadProxy::SetOutputSurface(scoped_ptr<OutputSurface> output_surface) {
                  impl_thread_weak_ptr_, base::Passed(&output_surface)));
 }
 
+scoped_ptr<OutputSurface> ThreadProxy::GetOutputSurface() {

[no sievers, 2015/09/10 00:00:22]

impl().scheduler->DidLoseOutputSurface();

[no sievers, 2015/09/10 01:26:24]

You'll have to post this to the impl thread and then block on it, see for
example FinishAllRendering().

[sohanjg, 2015/09/10 15:07:23]

You mean both DidLoseOutputSurface, and Get/ReleaseOS shud be called in impl
thread, right ?
But, we are expecting to return the OS from this call.
I have maintained OS as a member in ThreadProxy, so that both the threads have
access to modify it.
We are protected as main will not read till impl has completed writing it.

+  return impl().layer_tree_host_impl->GetOutputSurface();
+}
+
 void ThreadProxy::DidInitializeOutputSurface(
     bool success,
     const RendererCapabilities& capabilities) {