Add FilePath to base namespace.

chrome/browser/chromeos/drive/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_DRIVE_FILE_SYSTEM_OBSERVER_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_FILE_SYSTEM_OBSERVER_H_
 
 #include "chrome/browser/chromeos/drive/drive_file_error.h"
 
+namespace base {
 class FilePath;
+}
 
 namespace drive {
 
 // Interface for classes that need to observe events from classes implementing
 // DriveFileSystemInterface.
 // All events are notified on UI thread.
 class DriveFileSystemObserver {
  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 FilePath& directory_path) {
+  virtual void OnDirectoryChanged(const base::FilePath& directory_path) {
   }
 
   // Triggered when the file system is initially loaded.
   virtual void OnInitialLoadFinished(DriveFileError error) {
   }
 
   // Triggered when a document feed is fetched. |num_accumulated_entries|
   // tells the number of entries fetched so far.
   virtual void OnResourceListFetched(int num_accumulated_entries) {
   }
@@ skipping 10 matching lines @@
   virtual void OnFileSystemBeingUnmounted() {
   }
 
  protected:
   virtual ~DriveFileSystemObserver() {}
 };
 
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_FILE_SYSTEM_OBSERVER_H_