Add ExtensionsTestBrowserContext class for test.

extensions/extensions.gyp

 # Copyright 2013 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': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 644 matching lines @@
         '../testing/gtest.gyp:gtest',
         'common/api/api.gyp:extensions_api',
         'extensions_browser',
         'extensions_common',
       ],
       'include_dirs': [
         '..',
         '<(SHARED_INTERMEDIATE_DIR)',
       ],
       'sources': [
+        'browser/extensions_test_browser_context.cc',
+        'browser/extensions_test_browser_context.h',
         'browser/test_extensions_browser_client.cc',
         'browser/test_extensions_browser_client.h',
         'browser/test_management_policy.cc',
         'browser/test_management_policy.h',
         'browser/test_runtime_api_delegate.cc',
         'browser/test_runtime_api_delegate.h',
         'common/extension_builder.cc',
         'common/extension_builder.h',
         'common/test_util.cc',
         'common/test_util.h',
@@ skipping 60 matching lines @@
               '<(SHARED_INTERMEDIATE_DIR)/extensions/extensions_renderer_resources.pak',
             ],
             'pak_output': '<(PRODUCT_DIR)/extensions_unittests_resources.pak',
           },
           'includes': [ '../build/repack_action.gypi' ],
         },
       ],
     },
   ]
 }