Allow extension APIs to be compiled out.

chrome/chrome_tests.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.
 {
   'variables' : {
     'pyautolib_sources': [
       'app/chrome_command_ids.h',
       'app/chrome_dll_resource.h',
       'common/automation_constants.h',
       'common/pref_names.cc',
@@ skipping 2128 matching lines @@
             'nacl/nacl_ipc_adapter_unittest.cc',
             'nacl/nacl_validation_query_unittest.cc',
           ],
         }],
         ['target_arch!="arm"', {
           'dependencies': [
             # build time dependency.
             '../v8/tools/gyp/v8.gyp:v8_shell#host',
           ],
         }],
+        ['enable_extensions==0', {
+          'sources/': [
+            ['exclude', '^browser/extensions/api/'],
+            ['exclude', '^browser/extensions/extension_idle_api_unittest.cc'],
+            ['exclude', '^browser/extensions/extension_omnibox_unittest.cc'],
+          ],
+        }],
         ['use_aura==1', {
           'dependencies': [
             '../ui/aura/aura.gyp:test_support_aura',
           ],
           'sources/': [
             ['exclude', '^browser/automation/automation_provider_unittest.cc'],
             ['exclude', '^browser/accessibility/browser_accessibility_win_unittest.cc'],
             ['exclude', '^browser/ui/views/extensions/browser_action_drag_data_unittest.cc'],
             ['exclude', '^browser/ui/views/select_file_dialog_win_unittest.cc'],
             ['exclude', '^browser/ui/views/bookmarks/bookmark_editor_view_unittest.cc'],
@@ skipping 2492 matching lines @@
               # Use outputs of this action as inputs for the main target build.
               # Seems as a misnomer but makes this happy on Linux (scons).
               'process_outputs_as_sources': 1,
             },
           ],  # 'actions'
         },
       ]
     }],  # 'coverage!=0'
   ],  # 'conditions'
 }