Files.app: Provide detailed change information on onDirectoryChanged event

chrome/browser/chromeos/drive/file_system_observer.h

 // Copyright (c) 2012 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_DRIVE_FILE_SYSTEM_OBSERVER_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_FILE_SYSTEM_OBSERVER_H_
 
 #include "chrome/browser/chromeos/drive/file_errors.h"
 #include "chrome/browser/chromeos/drive/file_system/operation_observer.h"
 
 namespace base {
 class FilePath;
 }
 
 namespace drive {
 
+class FileChange;
+
 // Interface for classes that need to observe events from classes implementing
 // FileSystemInterface.
 // All events are notified on UI thread.
 class FileSystemObserver {
  public:
   // Triggered when a content of a directory has been changed.
   // |directory_path| is a virtual directory path (/drive/...) representing
   // changed directory.
   virtual void OnDirectoryChanged(const base::FilePath& directory_path) {}
+  virtual void OnFileChanged(const FileChange& file_change) {}
 
   // Triggared when a specific drive error occurred.
   // |type| is a type of the error. |file_name| is a virtual path of the entry.
   virtual void OnDriveSyncError(file_system::DriveSyncErrorType type,
                                 const base::FilePath& file_path) {}
 
  protected:
   virtual ~FileSystemObserver() {}
 };
 
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_FILE_SYSTEM_OBSERVER_H_