Shortcut a couple of IPCs when the task manager is disabled.

chrome/browser/task_manager/task_manager.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 CHROME_BROWSER_TASK_MANAGER_TASK_MANAGER_H_
 #define CHROME_BROWSER_TASK_MANAGER_TASK_MANAGER_H_
 
 #include <map>
 #include <vector>
 
@@ skipping 432 matching lines @@
   void BytesRead(BytesReadParam param);
 
   void MultipleBytesRead(const std::vector<BytesReadParam>* params);
 
   // Notifies the UI thread about all the bytes read. Allows for coalescing
   // multiple bytes read into a single task for the UI thread. This is important
   // for when downloading a lot of data on the IO thread, since posting a Task
   // for each one is expensive.
   void NotifyMultipleBytesRead();
 
+  // Called on the IO thread to start/stop updating byte counts.
+  void StartUpdatingByteCount();
+  void StopUpdatingByteCount();
+
   // Returns the network usage (in byte per second) that should be displayed for
   // the passed |resource|.  -1 means the information is not available for that
   // resource.
   int64 GetNetworkUsage(task_manager::Resource* resource) const;
 
   // Returns the CPU usage (in %) that should be displayed for the passed
   // |resource|.
   double GetCPUUsage(task_manager::Resource* resource) const;
 
   // Returns the idle wakeups that should be displayed for the passed
@@ skipping 63 matching lines @@
   // StopUpdating.
   int update_requests_;
 
   // How many calls to StartListening have been made without matching calls to
   // StopListening.
   int listen_requests_;
 
   // Whether we are currently in the process of updating.
   UpdateState update_state_;
 
+  // Whether the IO thread is currently in the process of updating.
+  bool is_updating_byte_count_;

[Lei Zhang, 2014/09/06 06:17:47]

nit: Mention this is only accessed on the IO thread.

[tonyg, 2014/09/08 18:59:38]

Done.

+
   // A salt lick for the goats.
   uint64 goat_salt_;
 
   // Buffer for coalescing BytesReadParam so we don't have to post a task on
   // each NotifyBytesRead() call.
   std::vector<BytesReadParam> bytes_read_buffer_;
 
   std::vector<base::Closure> on_data_ready_callbacks_;
 
   // All per-Resource values are stored here.
   mutable PerResourceCache per_resource_cache_;
 
   // All per-Process values are stored here.
   mutable PerProcessCache per_process_cache_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskManagerModel);
 };
 
 #endif  // CHROME_BROWSER_TASK_MANAGER_TASK_MANAGER_H_