cc: Setup API to release OutputSurface from LTHClient.

cc/trees/layer_tree_host_impl.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/layer_tree_host_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <set>
@@ skipping 2137 matching lines @@
                                              main_frame_events.Pass());
 }
 
 void LayerTreeHostImpl::CleanUpTileManager() {
   tile_manager_->FinishTasksAndCleanUp();
   resource_pool_ = nullptr;
   tile_task_worker_pool_ = nullptr;
   single_thread_synchronous_task_graph_runner_ = nullptr;
 }
 
-bool LayerTreeHostImpl::InitializeRenderer(
-    scoped_ptr<OutputSurface> output_surface) {
-  TRACE_EVENT0("cc", "LayerTreeHostImpl::InitializeRenderer");
-
+scoped_ptr<OutputSurface> LayerTreeHostImpl::ReleaseOutputSurface() {
   // Since we will create a new resource provider, we cannot continue to use
   // the old resources (i.e. render_surfaces and texture IDs). Clear them
   // before we destroy the old resource provider.
   ReleaseTreeResources();
 
   // Note: order is important here.
   renderer_ = nullptr;
   CleanUpTileManager();
   resource_provider_ = nullptr;
-  output_surface_ = nullptr;
 
+  return output_surface_.Pass();
+}
+
+bool LayerTreeHostImpl::InitializeRenderer(
+    scoped_ptr<OutputSurface> output_surface) {
+  TRACE_EVENT0("cc", "LayerTreeHostImpl::InitializeRenderer");
+
+  ReleaseOutputSurface();
   if (!output_surface->BindToClient(this)) {
     // Avoid recreating tree resources because we might not have enough
     // information to do this yet (eg. we don't have a TileManager at this
     // point).
     return false;
   }
 
   output_surface_ = output_surface.Pass();
   resource_provider_ = ResourceProvider::Create(
       output_surface_.get(), shared_bitmap_manager_, gpu_memory_buffer_manager_,
@@ skipping 1429 matching lines @@
   if (active_tree()) {
     LayerAnimationValueProvider* layer = active_tree()->LayerById(layer_id);
     if (layer)
       return layer->ScrollOffsetForAnimation();
   }
 
   return gfx::ScrollOffset();
 }
 
 }  // namespace cc