Make Task Manager sort more meaningful

chrome/browser/task_management/task_manager_interface.h

 // Copyright 2015 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_MANAGEMENT_TASK_MANAGER_INTERFACE_H_
 #define CHROME_BROWSER_TASK_MANAGEMENT_TASK_MANAGER_INTERFACE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 171 matching lines @@
   virtual bool GetV8Memory(TaskId task_id,
                            int64_t* allocated,
                            int64_t* used) const = 0;
 
   // Gets the Webkit resource cache stats for the task with |task_id|.
   // A return value of false means that task does NOT report WebCache stats.
   virtual bool GetWebCacheStats(
       TaskId task_id,
       blink::WebCache::ResourceTypeStats* stats) const = 0;
 
-  // Gets the list of task IDs currently tracked by the task manager. The list
-  // will be sorted such that the task representing the browser process is at
-  // the top of the list and the rest of the IDs will be sorted by the process
-  // IDs on which the tasks are running, then by the task IDs themselves.
+  // Gets the list of task IDs currently tracked by the task manager. Tasks that
+  // share the same process id will always be consecutive. The list will be
+  // sorted in a way that reflects the process tree: the browser process will be
+  // first, followed by the gpu process if it exists. Related processes (e.g., a
+  // subframe process and its parent) will be kept together if possible. Callers
+  // can expect this ordering to be stable when a process is added or removed.
   virtual const TaskIdList& GetTaskIdsList() const = 0;
 
   // Gets the list of task IDs of the tasks that run on the same process as the
   // task with |task_id|. The returned list will at least include |task_id|.
   virtual TaskIdList GetIdsOfTasksSharingSameProcess(TaskId task_id) const = 0;
 
   // Gets the number of task-manager tasks running on the same process on which
   // the Task with |task_id| is running.
   virtual size_t GetNumberOfTasksOnSameProcess(TaskId task_id) const = 0;
 
@@ skipping 57 matching lines @@
 
   // The flags containing the enabled resources types calculations.
   int64_t enabled_resources_flags_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskManagerInterface);
 };
 
 }  // namespace task_management
 
 #endif  // CHROME_BROWSER_TASK_MANAGEMENT_TASK_MANAGER_INTERFACE_H_