Ensure tests have an active task runner

chrome/browser/apps/app_shim/extension_app_shim_handler_mac_unittest.cc

Index: chrome/browser/apps/app_shim/extension_app_shim_handler_mac_unittest.cc
diff --git a/chrome/browser/apps/app_shim/extension_app_shim_handler_mac_unittest.cc b/chrome/browser/apps/app_shim/extension_app_shim_handler_mac_unittest.cc
index 76500420469581bba9fcf66b43e150e71ceb4f1a..f361b7a69891f32c00a09365d3766c85d556ca8a 100644
--- a/chrome/browser/apps/app_shim/extension_app_shim_handler_mac_unittest.cc
+++ b/chrome/browser/apps/app_shim/extension_app_shim_handler_mac_unittest.cc
@@ -11,6 +11,7 @@
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/test/base/testing_profile.h"
 #include "content/public/browser/notification_service.h"
+#include "content/public/test/test_browser_thread_bundle.h"
 #include "extensions/common/extension.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -200,6 +201,7 @@ class ExtensionAppShimHandlerTest : public testing::Test {
                            std::vector<base::FilePath>());
   }
 
+  content::TestBrowserThreadBundle thread_bundle_;
   MockDelegate* delegate_;
   scoped_ptr<TestingExtensionAppShimHandler> handler_;
   base::FilePath profile_path_a_;