Add GPU memory tab to the task manager.

content/browser/gpu/gpu_data_manager_impl.h

Index: content/browser/gpu/gpu_data_manager_impl.h
diff --git a/content/browser/gpu/gpu_data_manager_impl.h b/content/browser/gpu/gpu_data_manager_impl.h
index 7104ed0d95190eacd2dbcd4d50dd6f100f436613..fbb33979aa3caf27ba29b4a71348150db4439e20 100644
--- a/content/browser/gpu/gpu_data_manager_impl.h
+++ b/content/browser/gpu/gpu_data_manager_impl.h
@@ -33,6 +33,7 @@ class CONTENT_EXPORT GpuDataManagerImpl
   virtual bool GpuAccessAllowed() OVERRIDE;
   virtual void RequestCompleteGpuInfoIfNeeded() OVERRIDE;
   virtual bool IsCompleteGPUInfoAvailable() const OVERRIDE;
+  virtual void RequestVidmemUsageStatsUpdate() OVERRIDE;
   virtual bool ShouldUseSoftwareRendering() OVERRIDE;
   virtual void RegisterSwiftShaderPath(const FilePath& path) OVERRIDE;
   virtual const base::ListValue& GetLogMessages() const OVERRIDE;
@@ -43,6 +44,9 @@ class CONTENT_EXPORT GpuDataManagerImpl
   // Only update if the current GPUInfo is not finalized.
   void UpdateGpuInfo(const content::GPUInfo& gpu_info);
 
+  void UpdateVidmemUsageStats(
+      const content::GPUVidmemUsageStats& vidmem_usage_stats);
+
   void AddLogMessage(Value* msg);
 
   // Insert disable-feature switches corresponding to preliminary gpu feature