Fix filesystem API file_handlers to work for drive on ChromeOS.

webkit/fileapi/file_system_types.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 WEBKIT_FILEAPI_FILE_SYSTEM_TYPES_H_
 #define WEBKIT_FILEAPI_FILE_SYSTEM_TYPES_H_
 
 #include "third_party/WebKit/Source/Platform/chromium/public/WebFileSystem.h"
 
 namespace fileapi {
@@ skipping 57 matching lines @@
   // Indicates media filesystem to which we need special protocol to access,
   // such as MTP or PTP.
   kFileSystemTypeDeviceMedia,
 
   // Indicates a Drive filesystem which provides access to Google Drive.
   kFileSystemTypeDrive,
 
   // Indicates a Syncable sandboxed filesystem which can be backed by a
   // cloud storage service.
   kFileSystemTypeSyncable,
+
+  // Indicates an external filesystem but with
+  kFileSystemTypeExternalFullPath,
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_FILE_SYSTEM_TYPES_H_