Exclude chrome/common/extensions/api/ from build if enable_extensions==0

chrome/chrome_tests_unit.gypi

 # Copyright 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': [
     {
       # This target contains mocks and test utilities that don't belong in
       # production libraries but are used by more than one test executable.
       'target_name': 'test_support_common',
       'type': 'static_library',
@@ skipping 1711 matching lines @@
         ['target_arch!="arm" and OS!="ios"', {
           'dependencies': [
             # build time dependency.
             '../v8/tools/gyp/v8.gyp:v8_shell#host',
           ],
         }],
         ['enable_extensions==0', {
           'sources/': [
             ['exclude', '^browser/extensions/api/'],
             ['exclude', '^browser/sync/glue/chrome_extensions_activity_monitor_unittest.cc'],
+            ['exclude', '^common/extensions/api/'],
           ],
         }],
         ['use_ash==1', {
           'sources': [
             'browser/ui/app_list/apps_model_builder_unittest.cc',
           ],
           'dependencies': [
             '../ash/ash.gyp:ash_resources',
             '../ash/ash.gyp:test_support_ash',
           ],
@@ skipping 559 matching lines @@
             'unit_tests.isolate',
           ],
           'sources': [
             'unit_tests.isolate',
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }