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

chrome/chrome_common.gypi

 # 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': [
     {
       'target_name': 'common',
       'type': 'static_library',
       'variables': {
@@ skipping 194 matching lines @@
         'common/extensions/unpacker.cc',
         'common/extensions/unpacker.h',
         'common/extensions/update_manifest.cc',
         'common/extensions/update_manifest.h',
         'common/extensions/user_script.cc',
         'common/extensions/user_script.h',
         'common/extensions/value_counter.cc',
         'common/extensions/value_counter.h',
         'common/extensions/api/extension_api.cc',
         'common/extensions/api/extension_api.h',
+        'common/extensions/api/extension_api_stub.cc',
         'common/external_ipc_fuzzer.h',
         'common/external_ipc_fuzzer.cc',
         'common/favicon_url.cc',
         'common/favicon_url.h',
         'common/form_data.cc',
         'common/form_data.h',
         'common/form_data_predictions.cc',
         'common/form_data_predictions.h',
         'common/form_field_data.cc',
         'common/form_field_data.h',
@@ skipping 191 matching lines @@
             '../third_party/mach_override/mach_override.gyp:mach_override',
           ],
           'include_dirs': [
             '../third_party/GTM',
           ],
           'sources!': [
             'common/child_process_logging_posix.cc',
             'common/chrome_version_info_posix.cc',
           ],
         }],
+        ['enable_extensions==1', {
+          'sources!': [
+            'common/extensions/api/extension_api_stub.cc',
+          ],
+        }, {  # enable_extensions == 0
+          'sources/': [
+            ['exclude', '^common/extensions/api/'],
+            ['include', 'common/extensions/api/extension_api_stub.cc'],
+          ],
+        }],
         ['remoting==1', {
           'dependencies': [
             '../remoting/remoting.gyp:remoting_client_plugin',
           ],
         }],
       ],
       'target_conditions': [
         ['OS == "ios"', {
           'sources/': [
             # Pull in specific Mac files for iOS (which have been filtered out
@@ skipping 165 matching lines @@
         'common/metrics/proto/user_action_event.proto',
       ],
       'variables': {
         'proto_in_dir': 'common/metrics/proto',
         'proto_out_dir': 'chrome/common/metrics/proto',
       },
       'includes': [ '../build/protoc.gypi' ],
     },
   ],
 }