Create a new base/message_loop directory and move the message_loop_proxy.

base/base.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'includes': [
     '../build/win_precompile.gypi',
@@ skipping 494 matching lines @@
         'memory/linked_ptr_unittest.cc',
         'memory/ref_counted_memory_unittest.cc',
         'memory/ref_counted_unittest.cc',
         'memory/scoped_nsobject_unittest.mm',
         'memory/scoped_ptr_unittest.cc',
         'memory/scoped_ptr_unittest.nc',
         'memory/scoped_vector_unittest.cc',
         'memory/singleton_unittest.cc',
         'memory/weak_ptr_unittest.cc',
         'memory/weak_ptr_unittest.nc',
-        'message_loop_proxy_impl_unittest.cc',
-        'message_loop_proxy_unittest.cc',
+        'message_loop/message_loop_proxy_impl_unittest.cc',
+        'message_loop/message_loop_proxy_unittest.cc',
         'message_loop_unittest.cc',
         'message_pump_glib_unittest.cc',
         'message_pump_io_ios_unittest.cc',
         'message_pump_libevent_unittest.cc',
         'metrics/sample_map_unittest.cc',
         'metrics/sample_vector_unittest.cc',
         'metrics/bucket_ranges_unittest.cc',
         'metrics/field_trial_unittest.cc',
         'metrics/histogram_base_unittest.cc',
         'metrics/histogram_unittest.cc',
@@ skipping 693 matching lines @@
             'base_unittests.isolate',
           ],
           'sources': [
             'base_unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }