Ensure tests have an active task runner

chrome/browser/ui/android/tab_model/tab_model_unittest.cc

Index: chrome/browser/ui/android/tab_model/tab_model_unittest.cc
diff --git a/chrome/browser/ui/android/tab_model/tab_model_unittest.cc b/chrome/browser/ui/android/tab_model/tab_model_unittest.cc
index 8f099e0a2b23c6541301c1220229089351074206..103c08c54ee1ccf21a7edc173be6d012bba1fd8c 100644
--- a/chrome/browser/ui/android/tab_model/tab_model_unittest.cc
+++ b/chrome/browser/ui/android/tab_model/tab_model_unittest.cc
@@ -8,10 +8,13 @@
 #include "chrome/test/base/testing_profile.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_source.h"
+#include "content/public/test/test_browser_thread_bundle.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-typedef testing::Test TabModelTest;
+class TabModelTest : public testing::Test {
+  content::TestBrowserThreadBundle thread_bundle_;
+};
 
 namespace {
 class TabModelAndroidProfileMock : public TestingProfile {