base::Bind: Convert FilePathWatcher.

base/files/file_path_watcher.h

 // 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.
 
 // This module provides a way to monitor a file or directory for changes.
 
 #ifndef BASE_FILES_FILE_PATH_WATCHER_H_
 #define BASE_FILES_FILE_PATH_WATCHER_H_
 #pragma once
 
@@ skipping 22 matching lines @@
   // 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 OnFilePathError(const FilePath& path) {}
   };
 
-  FilePathWatcher();
-  ~FilePathWatcher();
-
-  // Register interest in any changes on |path|. OnPathChanged will be called
-  // back for each change. Returns true on success.
-  // OnFilePathChanged() will be called on the same thread as Watch() is called,
-  // which should have a MessageLoop of TYPE_IO.
-  bool Watch(const FilePath& path, Delegate* delegate) WARN_UNUSED_RESULT;
-
-  class PlatformDelegate;
-
-  // A custom Task that always cleans up the PlatformDelegate, either when
-  // executed or when deleted without having been executed at all, as can
-  // happen during shutdown.
-  class CancelTask : public Task {
-   public:
-    CancelTask(PlatformDelegate* delegate): delegate_(delegate) {}
-    virtual ~CancelTask() {
-      delegate_->CancelOnMessageLoopThread();
-    }
-
-    virtual void Run() OVERRIDE {
-      delegate_->CancelOnMessageLoopThread();
-    }
-   private:
-    scoped_refptr<PlatformDelegate> delegate_;
-
-    DISALLOW_COPY_AND_ASSIGN(CancelTask);
-  };
-
   // Used internally to encapsulate different members on different platforms.
+  // TODO(jhawkins): Move this into its own file. Also fix the confusing naming
+  // wrt Delegate vs PlatformDelegate.
   class PlatformDelegate : public base::RefCountedThreadSafe<PlatformDelegate> {
    public:
     PlatformDelegate();
 
     // 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.
     // It can be called from any thread.
     virtual void Cancel() = 0;
 
    protected:
+    friend class FilePathWatcher;
+
     virtual ~PlatformDelegate();
 
     // Stop watching. This is only called on the thread of the appropriate
     // message loop. Since it can also be called more than once, it should
     // check |is_cancelled()| to avoid duplicate work.
     virtual void CancelOnMessageLoopThread() = 0;
 
     scoped_refptr<base::MessageLoopProxy> message_loop() const {
       return message_loop_;
     }
 
     void set_message_loop(base::MessageLoopProxy* loop) {
       message_loop_ = loop;
     }
 
     // Must be called before the PlatformDelegate is deleted.
     void set_cancelled() {
       cancelled_ = true;
     }
 
     bool is_cancelled() const {
       return cancelled_;
     }
 
    private:
     friend class base::RefCountedThreadSafe<PlatformDelegate>;
-    friend class CancelTask;
 
     scoped_refptr<base::MessageLoopProxy> message_loop_;
     bool cancelled_;
   };
 
+  FilePathWatcher();
+  ~FilePathWatcher();
+
+  // A callback that always cleans up the PlatformDelegate, either when executed
+  // or when deleted without having been executed at all, as can happen during
+  // shutdown.
+  static void CancelWatch(const scoped_refptr<PlatformDelegate>& delegate);
+
+  // Register interest in any changes on |path|. OnPathChanged will be called
+  // back for each change. Returns true on success.
+  // OnFilePathChanged() will be called on the same thread as Watch() is called,
+  // which should have a MessageLoop of TYPE_IO.
+  bool Watch(const FilePath& path, Delegate* delegate) WARN_UNUSED_RESULT;
+
  private:
   scoped_refptr<PlatformDelegate> impl_;
 
   DISALLOW_COPY_AND_ASSIGN(FilePathWatcher);
 };
 
 }  // namespace files
 }  // namespace base
 
 #endif  // BASE_FILES_FILE_PATH_WATCHER_H_