Add truncate and cancel for FileWriter; write and tests will come in later CL...

webkit/fileapi/file_system_callback_dispatcher.h

 // Copyright (c) 2010 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_CALLBACK_DISPATCHER_H_
 #define WEBKIT_FILEAPI_FILE_SYSTEM_CALLBACK_DISPATCHER_H_
 
 #include <vector>
 
 #include "base/file_util_proxy.h"
@@ skipping 23 matching lines @@
       const std::vector<base::file_util_proxy::Entry>& entries,
       bool has_more) = 0;
 
   // Callback for opening a file system. Called with a name and root path for
   // the FileSystem when the request is accepted. Used by WebFileSystem API.
   virtual void DidOpenFileSystem(const std::string& name,
                                  const FilePath& root_path) = 0;
 
   // Called with an error code when a requested operation has failed.
   virtual void DidFail(base::PlatformFileError error_code) = 0;
+
+  // Callback for FileWriter's write() call.
+  virtual void DidWrite(int64 bytes, bool complete) = 0;
 };
 
 } // namespace fileapi
 
 #endif  //  WEBKIT_FILEAPI_FILE_SYSTEM_CALLBACK_DISPATCHER_H_