[fsp] Add support for truncating files.

chrome/browser/chromeos/file_system_provider/request_manager.cc

 // Copyright 2014 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.
 
 #include "chrome/browser/chromeos/file_system_provider/request_manager.h"
 
 #include "base/debug/trace_event.h"
 #include "base/files/file.h"
 #include "base/stl_util.h"
 
@@ skipping 24 matching lines @@
     case CREATE_DIRECTORY:
       return "CREATE_DIRECTORY";
     case DELETE_ENTRY:
       return "DELETE_ENTRY";
     case CREATE_FILE:
       return "CREATE_FILE";
     case COPY_ENTRY:
       return "COPY_ENTRY";
     case MOVE_ENTRY:
       return "MOVE_ENTRY";
+    case TRUNCATE:
+      return "TRUNCATE";
     case TESTING:
       return "TESTING";
   }
   NOTREACHED();
   return "";
 }
 
 RequestManager::RequestManager(
     NotificationManagerInterface* notification_manager)
     : notification_manager_(notification_manager),
@@ skipping 177 matching lines @@
     notification_manager_->HideUnresponsiveNotification(request_id);
 
   FOR_EACH_OBSERVER(Observer, observers_, OnRequestDestroyed(request_id));
 
   TRACE_EVENT_ASYNC_END0(
       "file_system_provider", "RequestManager::Request", request_id);
 }
 
 }  // namespace file_system_provider
 }  // namespace chromeos