Fixed shutdown concurrency issues in FilePathWatcher.

chrome/browser/file_path_watcher/file_path_watcher.h

 // Copyright (c) 2010 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.
 
 // This module provides a way to monitor a file or directory for changes.
 
 #ifndef CHROME_BROWSER_FILE_PATH_WATCHER_FILE_PATH_WATCHER_H_
 #define CHROME_BROWSER_FILE_PATH_WATCHER_FILE_PATH_WATCHER_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/file_path.h"
 #include "base/ref_counted.h"
-#include "content/browser/browser_thread.h"
 
 // This class lets you register interest in changes on a FilePath.
 // The delegate will get called whenever the file or directory referenced by the
 // FilePath is changed, including created or deleted. Due to limitations in the
 // underlying OS APIs, spurious notifications might occur that don't relate to
 // an actual change to the watch target.
 class FilePathWatcher {
  public:
   // Declares the callback client code implements to receive notifications. Note
   // that implementations of this interface should not keep a reference to the
   // corresponding FileWatcher object to prevent a reference cycle.
   class Delegate : public base::RefCountedThreadSafe<Delegate> {
    public:
     virtual ~Delegate() {}
     virtual void OnFilePathChanged(const FilePath& path) = 0;
     // Called when platform specific code detected an error. The watcher will
     // not call OnFilePathChanged for future changes.
     virtual void OnError() {}
   };
 
   FilePathWatcher();
   ~FilePathWatcher();
 
   // Register interest in any changes on |path|. OnPathChanged will be called
   // back for each change. Returns true on success.

[Bernhard Bauer, 2011/03/15 22:00:07]

While you're at it, could you add a comment stating that this method should only
be called on the FILE thread?

[Joao da Silva, 2011/03/18 16:09:17]

Done.

   bool Watch(const FilePath& path, Delegate* delegate) WARN_UNUSED_RESULT;
 
   // Used internally to encapsulate different members on different platforms.
-  class PlatformDelegate
-      : public base::RefCountedThreadSafe<PlatformDelegate,
-                                          BrowserThread::DeleteOnFileThread> {
+  class PlatformDelegate: public base::RefCountedThreadSafe<PlatformDelegate> {
    public:
     // Start watching for the given |path| and notify |delegate| about changes.
     virtual bool Watch(const FilePath& path, Delegate* delegate)
         WARN_UNUSED_RESULT = 0;
 
     // Stop watching. This is called from FilePathWatcher's dtor in order to
     // allow to shut down properly while the object is still alive.
     virtual void Cancel() {}
 
    protected:
-    friend struct BrowserThread::DeleteOnThread<BrowserThread::FILE>;
-    friend class DeleteTask<PlatformDelegate>;
+    friend struct base::RefCountedThreadSafe<PlatformDelegate>;
 
     virtual ~PlatformDelegate() {}
   };
 
  private:
   scoped_refptr<PlatformDelegate> impl_;
 
   DISALLOW_COPY_AND_ASSIGN(FilePathWatcher);
 };
 
 #endif  // CHROME_BROWSER_FILE_PATH_WATCHER_FILE_PATH_WATCHER_H_