cc: Setup API to release OutputSurface from LTHClient.

cc/trees/thread_proxy.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/thread_proxy.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/auto_reset.h"
@@ skipping 199 matching lines @@
   layer_tree_host()->RequestNewOutputSurface();
 }
 
 void ThreadProxy::SetOutputSurface(scoped_ptr<OutputSurface> output_surface) {
   Proxy::ImplThreadTaskRunner()->PostTask(
       FROM_HERE,
       base::Bind(&ThreadProxy::InitializeOutputSurfaceOnImplThread,
                  impl_thread_weak_ptr_, base::Passed(&output_surface)));
 }
 
+scoped_ptr<OutputSurface> ThreadProxy::ReleaseOutputSurface() {

[danakj, 2015/09/17 18:43:55]

Can you DCHECK that LTH knows the OS is lost?

+  DCHECK(IsMainThread());
+  DebugScopedSetMainThreadBlocked main_thread_blocked(this);
+  CompletionEvent completion;
+  scoped_ptr<OutputSurface> output_surface;
+  Proxy::ImplThreadTaskRunner()->PostTask(
+      FROM_HERE,
+      base::Bind(&ThreadProxy::ReleaseOutputSurfaceOnImplThread,
+                 impl_thread_weak_ptr_, &completion, &output_surface));
+  completion.Wait();
+  return output_surface.Pass();

[danakj, 2015/09/17 18:43:55]

don't need Pass() on return

+}
+
 void ThreadProxy::DidInitializeOutputSurface(
     bool success,
     const RendererCapabilities& capabilities) {
   TRACE_EVENT0("cc", "ThreadProxy::DidInitializeOutputSurface");
   DCHECK(IsMainThread());
 
   if (!success) {
     layer_tree_host()->DidFailToInitializeOutputSurface();
     return;
   }
@@ skipping 845 matching lines @@
       FROM_HERE,
       base::Bind(&ThreadProxy::DidInitializeOutputSurface,
                  main_thread_weak_ptr_,
                  success,
                  capabilities));
 
   if (success)
     impl().scheduler->DidCreateAndInitializeOutputSurface();
 }
 
+void ThreadProxy::ReleaseOutputSurfaceOnImplThread(
+    CompletionEvent* completion,
+    scoped_ptr<OutputSurface>* output_surface) {
+  TRACE_EVENT0("cc", "ThreadProxy::ReleaseOutputSurfaceOnImplThread");

[danakj, 2015/09/17 18:43:55]

we didn't trace in the STP, i think i'd rather the trace be in LTHI.

+  DCHECK(IsImplThread());
+
+  impl().scheduler->DidLoseOutputSurface();

[danakj, 2015/09/17 18:43:55]

Can you comment saying that, unlike in DidLoseOutputSurfaceOnImplThread, we
don't need to call LayerTreeHost::DidLoseOutputSurface since it already knows?

+  *output_surface = impl().layer_tree_host_impl->ReleaseOutputSurface();
+  completion->Signal();
+}
+
 void ThreadProxy::FinishGLOnImplThread(CompletionEvent* completion) {
   TRACE_EVENT0("cc", "ThreadProxy::FinishGLOnImplThread");
   DCHECK(IsImplThread());
   if (impl().layer_tree_host_impl->output_surface()) {
     ContextProvider* context_provider =
         impl().layer_tree_host_impl->output_surface()->context_provider();
     if (context_provider)
       context_provider->ContextGL()->Finish();
   }
   completion->Signal();
@@ skipping 159 matching lines @@
 
 void ThreadProxy::PostFrameTimingEvents(
     scoped_ptr<FrameTimingTracker::CompositeTimingSet> composite_events,
     scoped_ptr<FrameTimingTracker::MainFrameTimingSet> main_frame_events) {
   DCHECK(IsMainThread());
   layer_tree_host()->RecordFrameTimingEvents(composite_events.Pass(),
                                              main_frame_events.Pass());
 }
 
 }  // namespace cc