[Extensions] Break up BaseFeatureProvider, create JSONFeatureProvider

extensions/extensions.gypi

 # Copyright 2015 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': {
     'extensions_common_constants_sources': [
       'common/constants.cc',
       'common/constants.h',
     ],
@@ skipping 64 matching lines @@
       'common/extension_urls.h',
       'common/extension_utility_messages.h',
       'common/extensions_client.cc',
       'common/extensions_client.h',
       'common/feature_switch.cc',
       'common/feature_switch.h',
       'common/features/api_feature.cc',
       'common/features/api_feature.h',
       'common/features/base_feature_provider.cc',
       'common/features/base_feature_provider.h',
+      'common/features/json_feature_provider.cc',
+      'common/features/json_feature_provider.h',
       'common/features/behavior_feature.cc',
       'common/features/behavior_feature.h',
       'common/features/complex_feature.cc',
       'common/features/complex_feature.h',
       'common/features/feature.cc',
       'common/features/feature.h',
       'common/features/feature_provider.cc',
       'common/features/feature_provider.h',
       'common/features/feature_util.h',
       'common/features/json_feature_provider_source.cc',
@@ skipping 1041 matching lines @@
       'test/result_catcher.h',
       'test/test_content_utility_client.cc',
       'test/test_content_utility_client.h',
       'test/test_extensions_client.cc',
       'test/test_extensions_client.h',
       'test/test_permission_message_provider.cc',
       'test/test_permission_message_provider.h',
     ],
   },
 }