cc: Get rid of LayerTreeHost::output_surface_lost_ state.

ui/compositor/compositor.h

 // Copyright (c) 2012 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.
 
 #ifndef UI_COMPOSITOR_COMPOSITOR_H_
 #define UI_COMPOSITOR_COMPOSITOR_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 193 matching lines @@
       NON_EXPORTED_BASE(public cc::LayerTreeHostSingleThreadClient) {
  public:
   Compositor(ui::ContextFactory* context_factory,
              scoped_refptr<base::SingleThreadTaskRunner> task_runner);
   ~Compositor() override;
 
   ui::ContextFactory* context_factory() { return context_factory_; }
 
   void AddSurfaceClient(uint32_t client_id);
   void RemoveSurfaceClient(uint32_t client_id);
-  const std::unordered_map<uint32_t, uint32_t>& SurfaceClientsForTesting() {
-    return surface_clients_;
-  }
 
   void SetOutputSurface(std::unique_ptr<cc::OutputSurface> surface);
 
   // Schedules a redraw of the layer tree associated with this compositor.
   void ScheduleDraw();
 
   // Sets the root of the layer tree drawn by this Compositor. The root layer
   // must have no parent. The compositor's root layer is reset if the root layer
   // is destroyed. NULL can be passed to reset the root layer, in which case the
   // compositor will stop drawing anything.
@@ skipping 179 matching lines @@
   // The root of the Layer tree drawn by this compositor.
   Layer* root_layer_;
 
   base::ObserverList<CompositorObserver, true> observer_list_;
   base::ObserverList<CompositorAnimationObserver> animation_observer_list_;
 
   gfx::AcceleratedWidget widget_;
 #if defined(USE_AURA)
   ui::Window* window_;
 #endif
+  // A map from child id to parent id.
   std::unordered_map<uint32_t, uint32_t> surface_clients_;
   bool widget_valid_;
   bool output_surface_requested_;
   std::unique_ptr<cc::SurfaceIdAllocator> surface_id_allocator_;
   scoped_refptr<cc::Layer> root_web_layer_;
   std::unique_ptr<cc::LayerTreeHost> host_;
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
   // The manager of vsync parameters for this compositor.
   scoped_refptr<CompositorVSyncManager> vsync_manager_;
 
   // The device scale factor of the monitor that this compositor is compositing
   // layers on.
   float device_scale_factor_;
 
   bool locks_will_time_out_;
   CompositorLock* compositor_lock_;
 
   LayerAnimatorCollection layer_animator_collection_;
   scoped_refptr<cc::AnimationTimeline> animation_timeline_;
 
   base::WeakPtrFactory<Compositor> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Compositor);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_COMPOSITOR_H_