Move media library AutoTaskRunner to base and rename ScopedTaskRunner.

media/base/callback.cc

-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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.
 
 #include "media/base/callback.h"
 
 namespace media {
 
-AutoTaskRunner::~AutoTaskRunner() {
-  if (task_.get()) {
-    task_->Run();
-  }
-}
-
 AutoCallbackRunner::~AutoCallbackRunner() {
   if (callback_.get()) {
     callback_->Run();
   }
 }
 
 Callback0::Type* TaskToCallbackAdapter::NewCallback(Task* task) {
   return new TaskToCallbackAdapter(task);
 }
 
 TaskToCallbackAdapter::~TaskToCallbackAdapter() {}
 
 void TaskToCallbackAdapter::RunWithParams(const Tuple0& params) {
   task_->Run();
 }
 
 TaskToCallbackAdapter::TaskToCallbackAdapter(Task* task) : task_(task) {}
 
 }  // namespace media