cc: Make sure we don't insert or remove layers during painting

cc/trees/layer_tree_host.h

 // 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.
 
 #ifndef CC_TREES_LAYER_TREE_HOST_H_
 #define CC_TREES_LAYER_TREE_HOST_H_
 
 #include <limits>
 #include <set>
 #include <string>
@@ skipping 69 matching lines @@
     gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager = nullptr;
     TaskGraphRunner* task_graph_runner = nullptr;
     LayerTreeSettings const* settings = nullptr;
     scoped_refptr<base::SingleThreadTaskRunner> main_task_runner;
     scoped_ptr<BeginFrameSource> external_begin_frame_source;
 
     InitParams();
     ~InitParams();
   };
 
+  bool in_update() const { return in_update_; }
+
   // The SharedBitmapManager will be used on the compositor thread.
   static scoped_ptr<LayerTreeHost> CreateThreaded(
       scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner,
       InitParams* params);
 
   static scoped_ptr<LayerTreeHost> CreateSingleThreaded(
       LayerTreeHostSingleThreadClient* single_thread_client,
       InitParams* params);
   virtual ~LayerTreeHost();
 
@@ skipping 371 matching lines @@
   scoped_refptr<Layer> page_scale_layer_;
   scoped_refptr<Layer> inner_viewport_scroll_layer_;
   scoped_refptr<Layer> outer_viewport_scroll_layer_;
 
   LayerSelection selection_;
 
   SharedBitmapManager* shared_bitmap_manager_;
   gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager_;
   TaskGraphRunner* task_graph_runner_;
 
+  bool in_update_;
+
   ScopedPtrVector<SwapPromise> swap_promise_list_;
   std::set<SwapPromiseMonitor*> swap_promise_monitor_;
 
   PropertyTrees property_trees_;
 
   typedef base::hash_map<int, Layer*> LayerIdMap;
   LayerIdMap layer_id_map_;
 
   uint32_t surface_id_namespace_;
   uint32_t next_surface_sequence_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_H_