Improve error message for insecure 'content_security_policy' manifest entries.

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 1926 matching lines @@
         'common/extensions/extension_test_util.cc',
         'common/extensions/extension_unittest.cc',
         'common/extensions/features/feature_unittest.cc',
         'common/extensions/features/simple_feature_provider_unittest.cc',
         'common/extensions/manifest_tests/extension_manifest_test.cc',
         'common/extensions/manifest_tests/extension_manifests_auth_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_background_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_chromepermission_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_command_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_contentscript_unittest.cc',
+        'common/extensions/manifest_tests/extension_manifests_contentsecuritypolicy_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_default_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_devtools_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_excludematches_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_experimental_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_filebrowser_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_homepage_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_icon_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_initvalue_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_isolatedapp_unittest.cc',
         'common/extensions/manifest_tests/extension_manifests_launch_unittest.cc',
@@ skipping 2768 matching lines @@
                 '--result', '<@(_outputs)',
                 '--isolate', 'browser_tests.isolate',
               ],
             },
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }