Fixed shutdown concurrency issues in FilePathWatcher.

content/common/file_path_watcher/file_path_watcher.cc

 // 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.
 
 // Cross platform methods for FilePathWatcher. See the various platform
 // specific implementation files, too.
 
 #include "content/common/file_path_watcher/file_path_watcher.h"
 
 #include "base/logging.h"
 #include "base/message_loop.h"
 
 FilePathWatcher::~FilePathWatcher() {
   impl_->Cancel();
 }
 
 bool FilePathWatcher::Watch(const FilePath& path,
                             Delegate* delegate,
                             base::MessageLoopProxy* loop) {
   DCHECK(path.IsAbsolute());
   return impl_->Watch(path, delegate, loop);
 }
 
-FilePathWatcher::PlatformDelegate::PlatformDelegate() {
+FilePathWatcher::PlatformDelegate::PlatformDelegate(): cancelled_(false) {
 }
 
 FilePathWatcher::PlatformDelegate::~PlatformDelegate() {
+  DCHECK(is_cancelled());
 }
 
-void FilePathWatcher::DeletePlatformDelegate::Destruct(
-    const PlatformDelegate* delegate) {
-  scoped_refptr<base::MessageLoopProxy> loop = delegate->message_loop();
-  if (loop.get() == NULL || loop->BelongsToCurrentThread()) {
-    delete delegate;
-  } else {
-    loop->PostNonNestableTask(FROM_HERE,
-                              new DeleteTask<PlatformDelegate>(delegate));
-  }
-}