components: Extract pref_registry component out of user_prefs.

components/components.gyp

 # 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.
 
 {
   'variables': {
     # This turns on e.g. the filename-based detection of which
     # platforms to include source files on (e.g. files ending in
     # _mac.h or _mac.cc are only compiled on MacOSX).
     'chromium_code': 1,
@@ skipping 16 matching lines @@
     'json_schema.gypi',
     'keyed_service.gypi',
     'language_usage_metrics.gypi',
     'metrics.gypi',
     'navigation_metrics.gypi',
     'onc.gypi',
     'os_crypt.gypi',
     'password_manager.gypi',
     'policy.gypi',
     'precache.gypi',
+    'pref_registry.gypi',
     'query_parser.gypi',
     'rappor.gypi',
     'search_provider_logos.gypi',
     'signin.gypi',
     'startup_metric_utils.gypi',
     'translate.gypi',
     'url_matcher.gypi',
     'user_prefs.gypi',
     'variations.gypi',
     'webdata.gypi',
@@ skipping 24 matching lines @@
     ['android_webview_build == 0', {
       # Android WebView fails to build if a dependency on these targets is
       # introduced.
       'includes': [
         'sync_driver.gypi',
         'invalidation.gypi',
       ],
     }],
   ],
 }