Add support for almost-recursive watches in Linux DirectoryWatcher

base/directory_watcher_stub.cc

 // Copyright (c) 2009 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.
 
 // This file exists for Linux systems which don't have the inotify headers, and
 // thus cannot build directory_watcher_inotify.cc
 
 #include "base/directory_watcher.h"
 
 class DirectoryWatcherImpl : public DirectoryWatcher::PlatformDelegate {
  public:
   virtual bool Watch(const FilePath& path, DirectoryWatcher::Delegate* delegate,
-                     bool recursive) {
+                     MessageLoop* backend_loop, bool recursive) {
     return false;
   }
 };
 
 DirectoryWatcher::DirectoryWatcher() {
   impl_ = new DirectoryWatcherImpl();
 }