Implement temporary reference assignment with DisplayCompositor.

services/ui/surfaces/display_compositor.cc

 // Copyright 2015 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 "services/ui/surfaces/display_compositor.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
@@ skipping 85 matching lines @@
                                       child_frame_sink_id);
 }
 
 void DisplayCompositor::UnregisterFrameSinkHierarchy(
     const cc::FrameSinkId& parent_frame_sink_id,
     const cc::FrameSinkId& child_frame_sink_id) {
   manager_.UnregisterFrameSinkHierarchy(parent_frame_sink_id,
                                         child_frame_sink_id);
 }
 
+void DisplayCompositor::DropTemporaryReference(
+    const cc::SurfaceId& surface_id) {
+  manager_.DropTemporaryReference(surface_id);
+}
+
 std::unique_ptr<cc::Display> DisplayCompositor::CreateDisplay(
     const cc::FrameSinkId& frame_sink_id,
     gpu::SurfaceHandle surface_handle,
     cc::SyntheticBeginFrameSource* begin_frame_source) {
   scoped_refptr<cc::InProcessContextProvider> context_provider =
       new cc::InProcessContextProvider(
           gpu_service_, surface_handle, gpu_memory_buffer_manager_.get(),
           image_factory_, gpu::SharedMemoryLimits(),
           nullptr /* shared_context */);
 
@@ skipping 35 matching lines @@
 }
 
 void DisplayCompositor::DestroyCompositorFrameSink(cc::FrameSinkId sink_id) {
   compositor_frame_sinks_.erase(sink_id);
 }
 
 void DisplayCompositor::OnSurfaceCreated(const cc::SurfaceInfo& surface_info) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_GT(surface_info.device_scale_factor(), 0.0f);
 
+  // TODO(kylechar): |client_| will try to find an owner for the temporary
+  // reference to the new surface. With surface synchronization this might not
+  // be necessary, because a surface reference might already exist and no
+  // temporary reference was created. It could be useful to let |client_| know
+  // if it should find an owner.
   if (client_)
     client_->OnSurfaceCreated(surface_info);
 }
 
 void DisplayCompositor::OnSurfaceDamaged(const cc::SurfaceId& surface_id,
                                          bool* changed) {}
 
 void DisplayCompositor::OnClientConnectionLost(
     const cc::FrameSinkId& frame_sink_id,
     bool destroy_compositor_frame_sink) {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (destroy_compositor_frame_sink)
     DestroyCompositorFrameSink(frame_sink_id);
   // TODO(fsamuel): Tell the display compositor host that the client connection
   // has been lost so that it can drop its private connection and allow a new
   // client instance to create a new CompositorFrameSink.
 }
 
 void DisplayCompositor::OnPrivateConnectionLost(
     const cc::FrameSinkId& frame_sink_id,
     bool destroy_compositor_frame_sink) {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (destroy_compositor_frame_sink)
     DestroyCompositorFrameSink(frame_sink_id);
 }
 
 }  // namespace ui