Remove all remaining traces of MessageLoopProxy.

PRESUBMIT.py

 # 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.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
@@ skipping 260 matching lines @@
       (
         'Do not introduce new v8::Extensions into the code base, use',
         'gin::Wrappable instead. See http://crbug.com/334679',
       ),
       True,
       (
         r'extensions[\\\/]renderer[\\\/]safe_builtins\.*',
       ),
     ),
     (
-      '\<MessageLoopProxy\>',
-      (
-        'MessageLoopProxy is deprecated. ',
-        'Please use SingleThreadTaskRunner or ThreadTaskRunnerHandle instead.'
-      ),
-      True,
-      (
-        # Internal message_loop related code may still use it.
-        r'^base[\\\/]message_loop[\\\/].*',
-      ),
-    ),
-    (
       '#pragma comment(lib,',
       (
         'Specify libraries to link with in build files and not in the source.',
       ),
       True,
       (),
     ),
 )
 
 
@@ skipping 1923 matching lines @@
   results.extend(input_api.canned_checks.CheckTreeIsOpen(
       input_api,
       output_api,
       json_url='http://chromium-status.appspot.com/current?format=json'))
 
   results.extend(input_api.canned_checks.CheckChangeHasBugField(
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasDescription(
       input_api, output_api))
   return results