Revert of Allow ObserverListThreadSafe to be used from sequenced tasks.

base/android/application_status_listener_unittest.cc

Index: base/android/application_status_listener_unittest.cc
diff --git a/base/android/application_status_listener_unittest.cc b/base/android/application_status_listener_unittest.cc
index a6f098bc7b52e43c2825cfea8fce90f68b50e80f..803dedb128039ab0d7e35fbae3ffcd60879f6a25 100644
--- a/base/android/application_status_listener_unittest.cc
+++ b/base/android/application_status_listener_unittest.cc
@@ -69,9 +69,6 @@
         APPLICATION_STATE_HAS_DESTROYED_ACTIVITIES);
     event_.Wait();
     EXPECT_EQ(APPLICATION_STATE_HAS_DESTROYED_ACTIVITIES, state_);
-
-    // Delete |listener_| on the thread on which it was created.
-    thread_.task_runner()->DeleteSoon(FROM_HERE, listener_.release());
   }
 
  private: