Revert of Switch WindowedNotificationObserver to use base::RunLoop.

content/public/test/test_utils.cc

Index: content/public/test/test_utils.cc
diff --git a/content/public/test/test_utils.cc b/content/public/test/test_utils.cc
index 6eb901e74c8a56e7aad73fc6cc9c737f2d7c90c5..f0aa1317e24a5b27d6937ddea530b499df7ff7e3 100644
--- a/content/public/test/test_utils.cc
+++ b/content/public/test/test_utils.cc
@@ -291,8 +291,8 @@
     return;
 
   running_ = true;
-  run_loop_.reset(new base::RunLoop);
-  run_loop_->Run();
+  message_loop_runner_ = new MessageLoopRunner;
+  message_loop_runner_->Run();
   EXPECT_TRUE(seen_);
 }
 
@@ -309,7 +309,7 @@
   if (!running_)
     return;
 
-  run_loop_->Quit();
+  message_loop_runner_->Quit();
   running_ = false;
 }