Use base::MessageLoop in more files.

chrome/browser/printing/printer_query.cc

 // 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.
 
 #include "chrome/browser/printing/printer_query.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/message_loop.h"
 #include "base/threading/thread_restrictions.h"
@@ skipping 38 matching lines @@
 }
 
 PrintJobWorker* PrinterQuery::DetachWorker(PrintJobWorkerOwner* new_owner) {
   DCHECK(callback_.is_null());
   DCHECK(worker_.get());
 
   worker_->SetNewOwner(new_owner);
   return worker_.release();
 }
 
-MessageLoop* PrinterQuery::message_loop() {
+base::MessageLoop* PrinterQuery::message_loop() {
   return io_message_loop_;
 }
 
 const PrintSettings& PrinterQuery::settings() const {
   return settings_;
 }
 
 int PrinterQuery::cookie() const {
   return cookie_;
 }
@@ skipping 59 matching lines @@
 
 bool PrinterQuery::is_callback_pending() const {
   return !callback_.is_null();
 }
 
 bool PrinterQuery::is_valid() const {
   return worker_.get() != NULL;
 }
 
 }  // namespace printing