Introduce task_runner() accessors for both base::Thread and base::MessageLoop

base/threading/thread.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 BASE_THREADING_THREAD_H_
 #define BASE_THREADING_THREAD_H_
 
 #include <string>
 
 #include "base/base_export.h"
@@ skipping 125 matching lines @@
   // NOTE: You must not call this MessageLoop's Quit method directly.  Use
   // the Thread's Stop method instead.
   //
   MessageLoop* message_loop() const { return message_loop_; }
 
   // Returns a MessageLoopProxy for this thread.  Use the MessageLoopProxy's
   // PostTask methods to execute code on the thread.  This only returns
   // non-NULL after a successful call to Start. After Stop has been called,
   // this will return NULL. Callers can hold on to this even after the thread
   // is gone.
+  //
+  // Note: This method is deprecated. Callers should call task_runner() instead
+  // and use the TaskRunner interfaces for safely interfacing with the Thread.
   scoped_refptr<MessageLoopProxy> message_loop_proxy() const {
     return message_loop_ ? message_loop_->message_loop_proxy() : NULL;
   }
 
+  // Returns a TaskRunner for this thread. Use the TaskRunner's PostTask
+  // methods to execute code on the thread. This only returns non-NULL after

[awong, 2014/07/11 20:23:18]

How about "Returns NULL if thread is not running?

+  // a successfull call to Start. After Stop has been called, this will
+  // return NULL. Callers can hold on to this even after the thread is gone;
+  // in this situation, attempts to PostTask() will fail.
+  scoped_refptr<SingleThreadTaskRunner> task_runner() const {
+    return message_loop_proxy();
+  }
+
   // Returns the name of this thread (for display in debugger too).
   const std::string& thread_name() const { return name_; }
 
   // The native thread handle.
   PlatformThreadHandle thread_handle() { return thread_; }
 
   // The thread ID.
   PlatformThreadId thread_id() const { return thread_id_; }
 
   // Returns true if the thread has been started, and not yet stopped.
@@ skipping 64 matching lines @@
   std::string name_;
 
   friend void ThreadQuitHelper();
 
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 }  // namespace base
 
 #endif  // BASE_THREADING_THREAD_H_