Add GPU memory tab to the task manager.

content/public/browser/gpu_data_manager_observer.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 CONTENT_PUBLIC_BROWSER_GPU_DATA_MANAGER_OBSERVER_H_
 #define CONTENT_PUBLIC_BROWSER_GPU_DATA_MANAGER_OBSERVER_H_
 
 #include "content/common/content_export.h"
+#include "content/public/common/gpu_memory_stats.h"
 
 namespace content {
 
 // Observers can register themselves via GpuDataManager::AddObserver, and
 // can un-register with GpuDataManager::RemoveObserver.
 class GpuDataManagerObserver {
  public:
   // Called for any observers whenever there is a GPU info update.
   virtual void OnGpuInfoUpdate() = 0;
 
+  // Called for any observers whenever there is a GPU video memory update.
+  virtual void OnVideoMemoryUsageStatsUpdate(
+      const GPUVideoMemoryUsageStats& video_memory_usage_stats) = 0;
+
  protected:
   virtual ~GpuDataManagerObserver() {}
 };
 
 };  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_GPU_DATA_MANAGER_OBSERVER_H_