Revert of Convert more test helpers to base::RunLoop, fix page title checks.

content/public/test/browser_test_base.cc

Index: content/public/test/browser_test_base.cc
diff --git a/content/public/test/browser_test_base.cc b/content/public/test/browser_test_base.cc
index cdfde3472a60256e4106913da06c327079886974..2333cceee12396f5938785a2917750cb748aeeef 100644
--- a/content/public/test/browser_test_base.cc
+++ b/content/public/test/browser_test_base.cc
@@ -341,14 +341,7 @@
         TracingController::StartTracingDoneCallback());
   }
 
-  {
-    // This can be called from a posted task. Allow nested tasks here, because
-    // otherwise the test body will have to do it in order to use RunLoop for
-    // waiting.
-    base::MessageLoop::ScopedNestableTaskAllower allow(
-        base::MessageLoop::current());
-    RunTestOnMainThreadLoop();
-  }
+  RunTestOnMainThreadLoop();
 
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableTracing)) {