Revert "content: Remove use of MessageLoopProxy and deprecated MessageLoop APIs"

content/browser/plugin_loader_posix.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 CONTENT_BROWSER_PLUGIN_LOADER_POSIX_H_
 #define CONTENT_BROWSER_PLUGIN_LOADER_POSIX_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/time/time.h"
 #include "content/browser/plugin_service_impl.h"
 #include "content/public/browser/utility_process_host_client.h"
 #include "content/public/common/webplugininfo.h"
 #include "ipc/ipc_sender.h"
 
+namespace base {
+class MessageLoopProxy;
+}
+
 namespace content {
 class UtilityProcessHost;
 
 // This class is responsible for managing the out-of-process plugin loading on
 // POSIX systems. It primarily lives on the IO thread, but has a brief stay on
 // the FILE thread to iterate over plugin directories when it is first
 // constructed.
 //
 // The following is the algorithm used to load plugins:
 // 1. This asks the PluginList for the list of all potential plugins to attempt
@@ skipping 93 matching lines @@
   // True if there is (or is about to be) a utility process that loads plugins.
   bool loading_plugins_;
 
   friend class MockPluginLoaderPosix;
   DISALLOW_COPY_AND_ASSIGN(PluginLoaderPosix);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_PLUGIN_LOADER_POSIX_H_