Move media library AutoTaskRunner to base and rename ScopedTaskRunner.

media/base/callback.cc

Index: media/base/callback.cc
diff --git a/media/base/callback.cc b/media/base/callback.cc
index 484c74465449bf39b23199b00006ee580f1862b1..3daac8e229b16fa6a04d6559ba5056bb790f7de5 100644
--- a/media/base/callback.cc
+++ b/media/base/callback.cc
@@ -1,4 +1,4 @@
-// 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.
 
@@ -6,12 +6,6 @@
 
 namespace media {
 
-AutoTaskRunner::~AutoTaskRunner() {
-  if (task_.get()) {
-    task_->Run();
-  }
-}
-
 AutoCallbackRunner::~AutoCallbackRunner() {
   if (callback_.get()) {
     callback_->Run();