Keep event page alive when there's some Pepper plugin on it.

chrome/chrome_tests.gypi

 # 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': {
     'chrome_browser_extensions_test_support_sources': [
       # A list of sources which is shared between different browser tests.
       'browser/apps/app_browsertest_util.cc',
       'browser/apps/app_browsertest_util.h',
       'browser/extensions/browsertest_util.cc',
@@ skipping 2090 matching lines @@
                 'test/nacl/nacl_browsertest_util.cc',
                 'test/nacl/nacl_browsertest_util.h',
                 'test/nacl/pnacl_header_test.cc',
                 'test/nacl/pnacl_header_test.h',
               ],
               'dependencies': [
                 'test/data/nacl/nacl_test_data.gyp:*',
                 '../ppapi/native_client/native_client.gyp:nacl_irt',
                 '../ppapi/ppapi_nacl.gyp:ppapi_nacl_tests',
                 '../ppapi/tests/extensions/extensions.gyp:ppapi_tests_extensions_background_keepalive',
+                '../ppapi/tests/extensions/extensions.gyp:ppapi_tests_extensions_load_unload',
                 '../ppapi/tests/extensions/extensions.gyp:ppapi_tests_extensions_media_galleries',
                 '../ppapi/tests/extensions/extensions.gyp:ppapi_tests_extensions_packaged_app',
                 '../ppapi/tests/extensions/extensions.gyp:ppapi_tests_extensions_socket_permissions',
               ],
               'conditions': [
                 ['chromeos==1', {
                   'sources': [
                     '../third_party/liblouis/nacl_wrapper/liblouis_wrapper_browsertest.cc',
                   ],
                   'dependencies': [
@@ skipping 1122 matching lines @@
             ['enable_webrtc==1', {
               'dependencies': [
                 '../third_party/libjingle/libjingle.gyp:libjingle_webrtc'
               ]
             }],
           ],
         }]
     }],
   ],  # 'conditions'
 }