[content shell] only allow test plugins to load during layout tests

content/content_shell.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': {
     'content_shell_product_name': 'Content Shell',
     # The "19" is so that sites that sniff for version think that this is
     # something reasonably current; the "77.34.5" is a hint that this isn't a
     # standard Chrome.
@@ skipping 110 matching lines @@
         'shell/shell_javascript_dialog_win.cc',
         'shell/shell_javascript_dialog.h',
         'shell/shell_login_dialog_gtk.cc',
         'shell/shell_login_dialog_mac.mm',
         'shell/shell_login_dialog.cc',
         'shell/shell_login_dialog.h',
         'shell/shell_message_filter.cc',
         'shell/shell_message_filter.h',
         'shell/shell_network_delegate.cc',
         'shell/shell_network_delegate.h',
+        'shell/shell_plugin_service_filter.cc',
+        'shell/shell_plugin_service_filter.h',
         'shell/shell_quota_permission_context.cc',
         'shell/shell_quota_permission_context.h',
         'shell/shell_resource_dispatcher_host_delegate.cc',
         'shell/shell_resource_dispatcher_host_delegate.h',
         'shell/shell_url_request_context_getter.cc',
         'shell/shell_url_request_context_getter.h',
         'shell/shell_web_contents_view_delegate_android.cc',
         'shell/shell_web_contents_view_delegate_creator.h',
         'shell/shell_web_contents_view_delegate_gtk.cc',
         'shell/shell_web_contents_view_delegate_mac.mm',
@@ skipping 546 matching lines @@
             'native_lib_target': 'libcontent_shell_content_view',
             'additional_input_paths': ['<(PRODUCT_DIR)/content_shell/assets/content_shell.pak'],
             'asset_location': '<(ant_build_out)/content_shell/assets',
           },
           'includes': [ '../build/java_apk.gypi' ],
         },
       ],
     }],  # OS=="android"
   ]
 }