Add components/keyed_service to GN build.

components/keyed_service.gypi

 # Copyright 2014 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': [
     {
+      # GN version: //components/keyed_service/core:core
       'target_name': 'keyed_service_core',
       'type': '<(component)',
       'defines': [
         'KEYED_SERVICE_IMPLEMENTATION',
       ],
       'include_dirs': [
         '..',
       ],
       # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
       'msvs_disabled_warnings': [ 4267, ],
       'dependencies': [
         '../base/base.gyp:base',
       ],
       'sources': [
         'keyed_service/core/dependency_graph.cc',
         'keyed_service/core/dependency_graph.h',
         'keyed_service/core/dependency_node.h',
         'keyed_service/core/keyed_service.cc',
         'keyed_service/core/keyed_service.h',
         'keyed_service/core/keyed_service_export.h',
       ],
     },
   ],
   'conditions': [
     ['OS != "ios"', {
       'targets': [
         {
+          # GN version: //components/keyed_service/content:content
           'target_name': 'keyed_service_content',
           'type': '<(component)',
           'defines': [
             'KEYED_SERVICE_IMPLEMENTATION',
           ],
           # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
           'msvs_disabled_warnings': [ 4267, ],
           'dependencies': [
             'keyed_service_core',
             '../base/base.gyp:base',
@@ skipping 13 matching lines @@
             'keyed_service/content/browser_context_keyed_service_factory.cc',
             'keyed_service/content/browser_context_keyed_service_factory.h',
             'keyed_service/content/refcounted_browser_context_keyed_service.cc',
             'keyed_service/content/refcounted_browser_context_keyed_service.h',
             'keyed_service/content/refcounted_browser_context_keyed_service_factory.cc',
         ],
       }],
     }],
   ],
 }