Rename extension_manifest_keys namespace to extensions::manifest_keys.

chrome/chrome_common.gypi

 # Copyright (c) 2013 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.
 
 {
   'targets': [
     {
       'target_name': 'common',
       'type': 'static_library',
       'variables': {
@@ skipping 62 matching lines @@
         '../extensions/common/extension_resource.cc',
         '../extensions/common/extension_resource.h',
         '../extensions/common/extensions_client.cc',
         '../extensions/common/extensions_client.h',
         '../extensions/common/features/feature_provider.cc',
         '../extensions/common/features/feature_provider.h',
         '../extensions/common/id_util.cc',
         '../extensions/common/id_util.h',
         '../extensions/common/install_warning.cc',
         '../extensions/common/install_warning.h',
+        '../extensions/common/manifest_constants.cc',
+        '../extensions/common/manifest_constants.h',
         '../extensions/common/matcher/regex_set_matcher.cc',
         '../extensions/common/matcher/regex_set_matcher.h',
         '../extensions/common/matcher/string_pattern.cc',
         '../extensions/common/matcher/string_pattern.h',
         '../extensions/common/matcher/substring_set_matcher.cc',
         '../extensions/common/matcher/substring_set_matcher.h',
         '../extensions/common/matcher/url_matcher.cc',
         '../extensions/common/matcher/url_matcher.h',
         '../extensions/common/matcher/url_matcher_constants.cc',
         '../extensions/common/matcher/url_matcher_constants.h',
@@ skipping 751 matching lines @@
         'common/metrics/proto/user_action_event.proto',
       ],
       'variables': {
         'proto_in_dir': 'common/metrics/proto',
         'proto_out_dir': 'chrome/common/metrics/proto',
       },
       'includes': [ '../build/protoc.gypi' ],
     },
   ],
 }