[Extensions] Add extension feature generation code

tools/json_schema_compiler/test/json_schema_compiler_tests.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.
 
 {
   'targets': [
     {
       # GN version: //tools/json_schema_compiler:test
       'target_name': 'json_schema_compiler_tests',
       'type': 'static_library',
@@ skipping 27 matching lines @@
       ],
       'sources': [
         '<@(schema_files)',
         'test_util.cc',
         'test_util.h',
       ],
       'includes': ['../../../build/json_schema_compile.gypi'],
       # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
       'msvs_disabled_warnings': [4267, ],
     },
+    {
+      'target_name': 'feature_compiler_tests',
+      'type': 'static_library',
+      'variables': {
+        'feature_class': 'APIFeature',
+        'provider_class': 'TestAPIFeatureProvider',
+        'out_dir': 'tools/json_schema_compiler/test',
+        'out_base_filename': 'features_test',
+        'in_files': [
+          'tools/json_schema_compiler/test/features_test.json',
+          'tools/json_schema_compiler/test/features_test2.json',
+        ],
+      },
+      'inputs': ['<@(in_files)'],
+      'sources': ['<@(in_files)'],
+      'includes': ['../json_features.gypi'],
+    },
   ],
 }