Move FilePathWatcher to base/files.

content/common/file_path_watcher/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 CONTENT_COMMON_FILE_PATH_WATCHER_FILE_PATH_WATCHER_H_
-#define CONTENT_COMMON_FILE_PATH_WATCHER_FILE_PATH_WATCHER_H_
-#pragma once
-
-#include "base/basictypes.h"
-#include "base/file_path.h"
-#include "base/memory/ref_counted.h"
-#include "base/message_loop_proxy.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, FilePathWatcher has slightly different semantics on OS X
-// than on Windows or Linux. FilePathWatcher on Linux and Windows will detect
-// modifications to files in a watched directory. FilePathWatcher on Mac will
-// detect the creation and deletion of files in a watched directory, but will
-// not detect modifications to those files. See file_path_watcher_mac.cc for
-// details.
-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 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() {
-      delegate_->CancelOnMessageLoopThread();
-    }
-   private:
-    scoped_refptr<PlatformDelegate> delegate_;
-
-    DISALLOW_COPY_AND_ASSIGN(CancelTask);
-  };
-
-  // Used internally to encapsulate different members on different platforms.
-  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:
-    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_;
-  };
-
- private:
-  scoped_refptr<PlatformDelegate> impl_;
-
-  DISALLOW_COPY_AND_ASSIGN(FilePathWatcher);
-};
-
-#endif  // CONTENT_COMMON_FILE_PATH_WATCHER_FILE_PATH_WATCHER_H_