Rework FileWatcher to avoid race condition upon deletion.

chrome/browser/file_watcher_inotify.cc

 // 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.
 
 #include "chrome/browser/file_watcher.h"
 
 #include <errno.h>
 #include <string.h>
 #include <sys/inotify.h>
 #include <sys/ioctl.h>
@@ skipping 75 matching lines @@
 
   // Called for each event coming from the watch.
   void OnInotifyEvent(const inotify_event* event);
 
   // Start watching |path| for changes and notify |delegate| on each change.
   // Returns true if watch for |path| has been added successfully.
   virtual bool Watch(const FilePath& path, FileWatcher::Delegate* delegate);
 
  private:
   // Delegate to notify upon changes.
-  FileWatcher::Delegate* delegate_;
+  scoped_refptr<FileWatcher::Delegate> delegate_;
 
   // Watch returned by InotifyReader.
   InotifyReader::Watch watch_;
 
   // The file we're watching.
   FilePath path_;
 
   DISALLOW_COPY_AND_ASSIGN(FileWatcherImpl);
 };
 
-class FileWatcherImplNotifyTask : public Task {
- public:
-  FileWatcherImplNotifyTask(FileWatcher::Delegate* delegate,
-                            const FilePath& path)
-      : delegate_(delegate), path_(path) {
-  }
-
-  virtual void Run() {
-    delegate_->OnFileChanged(path_);
-  }
-
- private:
-  FileWatcher::Delegate* delegate_;
-  FilePath path_;
-
-  DISALLOW_COPY_AND_ASSIGN(FileWatcherImplNotifyTask);
-};
-
 class InotifyReaderTask : public Task {
  public:
   InotifyReaderTask(InotifyReader* reader, int inotify_fd, int shutdown_fd)
       : reader_(reader),
         inotify_fd_(inotify_fd),
         shutdown_fd_(shutdown_fd) {
   }
 
   virtual void Run() {
     while (true) {
@@ skipping 151 matching lines @@
   Singleton<InotifyReader>::get()->RemoveWatch(watch_, this);
 }
 
 void FileWatcherImpl::OnInotifyEvent(const inotify_event* event) {
   // Since we're watching the directory, filter out inotify events
   // if it's not related to the file we're watching.
   if (path_ != path_.DirName().Append(event->name))
     return;
 
   ChromeThread::PostTask(ChromeThread::FILE, FROM_HERE,
-      new FileWatcherImplNotifyTask(delegate_, path_));
+      NewRunnableMethod(delegate_.get(), &FileWatcher::Delegate::OnFileChanged,
+                        path_));
 }
 
 bool FileWatcherImpl::Watch(const FilePath& path,
                             FileWatcher::Delegate* delegate) {
   // Each FileWatcherImpl can only watch one file.
   DCHECK(watch_ == InotifyReader::kInvalidWatch);
 
   // It's not possible to watch a file that doesn't exist, so instead,
   // watch the parent directory.
   if (!file_util::PathExists(path.DirName()))
     return false;
 
   delegate_ = delegate;
   path_ = path;
   watch_ = Singleton<InotifyReader>::get()->AddWatch(path.DirName(), this);
   return watch_ != InotifyReader::kInvalidWatch;
 }
 
 }  // namespace
 
 FileWatcher::FileWatcher() {
   impl_ = new FileWatcherImpl();
 }