Add LayerTreeHostClient::{will,did}UpdateLayer, report layer updates to DevTools

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 <vector>
 
@@ skipping 235 matching lines @@
   }
 
   bool BlocksPendingCommit() const;
 
   // Obtains a thorough dump of the LayerTreeHost as a value.
   scoped_ptr<base::Value> AsValue() const;
 
   bool in_paint_layer_contents() const { return in_paint_layer_contents_; }
 
   bool UsingSharedMemoryResources();
+  int id() const { return tree_id_; }
 
  protected:
   LayerTreeHost(LayerTreeHostClient* client, const LayerTreeSettings& settings);
   bool Initialize(scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner);
   bool InitializeForTesting(scoped_ptr<Proxy> proxy_for_testing);
 
  private:
   bool InitializeProxy(scoped_ptr<Proxy> proxy);
 
   void PaintLayerContents(
@@ skipping 94 matching lines @@
     LCDTextMetrics()
         : total_num_cc_layers(0),
           total_num_cc_layers_can_use_lcd_text(0),
           total_num_cc_layers_will_use_lcd_text(0) {}
 
     int64 total_num_cc_layers;
     int64 total_num_cc_layers_can_use_lcd_text;
     int64 total_num_cc_layers_will_use_lcd_text;
   };
   LCDTextMetrics lcd_text_metrics_;
+  int tree_id_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_H_