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      1 // Copyright 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROME_BROWSER_CHROMEOS_DRIVE_FILE_WRITE_WATCHER_H_
      6 #define CHROME_BROWSER_CHROMEOS_DRIVE_FILE_WRITE_WATCHER_H_
      7 
      8 #include "base/callback_forward.h"
      9 #include "base/memory/scoped_ptr.h"
     10 #include "chrome/browser/chromeos/drive/file_system_util.h"
     11 
     12 namespace base {
     13 class FilePath;
     14 }  // namespace base
     15 
     16 namespace drive {
     17 
     18 namespace internal {
     19 
     20 typedef base::Callback<void(bool)> StartWatchCallback;
     21 
     22 // The class watches modification to Drive files in the cache directory.
     23 // This is used for returning a local writable snapshot of Drive files from the
     24 // Save-As file dialog, so that the callers of the dialog can save to Drive
     25 // without any special handling about Drive.
     26 class FileWriteWatcher {
     27  public:
     28   FileWriteWatcher();
     29   ~FileWriteWatcher();
     30 
     31   // Starts watching the modification to |path|. When it successfully started
     32   // watching, it runs |on_start_callback| by passing true as the argument.
     33   // Or if it failed, the callback is run with false.
     34   // Detected modification is notified by calling |on_write_callback|.
     35   //
     36   // Currently, the modification is watched in "one-shot" manner. That is, once
     37   // a modification is notified, the watch is deactivated for freeing system
     38   // resources. As a heuristic to capture the real end of write operations that
     39   // might be done by several chunked writes, the notification is fired after
     40   // 5 seconds has passed after the last write operation is detected.
     41   //
     42   // TODO(kinaba): investigate the possibility to continuously watch the whole
     43   // cache directory. http://crbug.com/269424
     44   void StartWatch(const base::FilePath& path,
     45                   const StartWatchCallback& on_start_callback,
     46                   const base::Closure& on_write_callback);
     47 
     48   // For testing purpose, stops inserting delay between the write detection and
     49   // notification to the |on_write_callback|.
     50   void DisableDelayForTesting();
     51 
     52  private:
     53   class FileWriteWatcherImpl;
     54   scoped_ptr<FileWriteWatcherImpl, util::DestroyHelper> watcher_impl_;
     55 
     56   DISALLOW_COPY_AND_ASSIGN(FileWriteWatcher);
     57 };
     58 
     59 }  // namespace internal
     60 }  // namespace drive
     61 
     62 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_FILE_WRITE_WATCHER_H_
     63