Rework FileWatcher to avoid race condition upon deletion.

chrome/browser/file_watcher_win.cc

 // Copyright (c) 2009 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 "chrome/browser/file_watcher.h"
 
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/object_watcher.h"
 #include "base/ref_counted.h"
 #include "base/time.h"
 
 namespace {
 
 class FileWatcherImpl : public FileWatcher::PlatformDelegate,
                         public base::ObjectWatcher::Delegate {
  public:
   FileWatcherImpl() : delegate_(NULL), handle_(INVALID_HANDLE_VALUE) {}
 
   virtual bool Watch(const FilePath& path, FileWatcher::Delegate* delegate);
 
   // Callback from MessageLoopForIO.
   virtual void OnObjectSignaled(HANDLE object);
 
  private:
   virtual ~FileWatcherImpl();
 
   // Delegate to notify upon changes.
-  FileWatcher::Delegate* delegate_;
+  scoped_refptr<FileWatcher::Delegate> delegate_;
 
   // Path we're watching (passed to delegate).
   FilePath path_;
 
   // Handle for FindFirstChangeNotification.
   HANDLE handle_;
 
   // ObjectWatcher to watch handle_ for events.
   base::ObjectWatcher watcher_;
 
@@ skipping 61 matching lines @@
   BOOL ok = FindNextChangeNotification(object);
   DCHECK(ok);
   watcher_.StartWatching(object, this);
 }
 
 }  // namespace
 
 FileWatcher::FileWatcher() {
   impl_ = new FileWatcherImpl();
 }