Revert of Revert "Revert of Reland: 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 4cc2bbbce8fdf89e4c09910fae5a1e35db7594d4..4fb9c669fa6dcf3bb7f75afc1fdf9effb173e5b4 100644
--- a/content/public/test/test_utils.cc
+++ b/content/public/test/test_utils.cc
@@ -304,8 +304,8 @@
     return;
 
   running_ = true;
-  run_loop_.reset(new base::RunLoop);
-  run_loop_->Run();
+  message_loop_runner_ = new MessageLoopRunner;
+  message_loop_runner_->Run();
   EXPECT_TRUE(seen_);
 }
 
@@ -322,7 +322,7 @@
   if (!running_)
     return;
 
-  run_loop_->Quit();
+  message_loop_runner_->Quit();
   running_ = false;
 }