Use a direct include of the message_loop header in content/, part 4.

content/renderer/pepper/pepper_device_enumeration_host_helper.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 "content/renderer/pepper/pepper_device_enumeration_host_helper.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/weak_ptr.h"
-#include "base/message_loop.h"
+#include "base/message_loop/message_loop.h"
 #include "ipc/ipc_message.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/host/dispatch_host_message.h"
 #include "ppapi/host/host_message_context.h"
 #include "ppapi/host/ppapi_host.h"
 #include "ppapi/host/resource_host.h"
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/shared_impl/ppb_device_ref_shared.h"
 #include "webkit/plugins/ppapi/plugin_delegate.h"
 
@@ skipping 170 matching lines @@
     bool succeeded,
     const std::vector<ppapi::DeviceRefData>& devices) {
   resource_host_->host()->SendUnsolicitedReply(
       resource_host_->pp_resource(),
       PpapiPluginMsg_DeviceEnumeration_NotifyDeviceChange(
           callback_id,
           succeeded ? devices : std::vector<ppapi::DeviceRefData>()));
 }
 
 }  // namespace content