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 2333cceee12396f5938785a2917750cb748aeeef..cdfde3472a60256e4106913da06c327079886974 100644
--- a/content/public/test/browser_test_base.cc
+++ b/content/public/test/browser_test_base.cc
@@ -341,7 +341,14 @@ void BrowserTestBase::ProxyRunTestOnMainThreadLoop() {
         TracingController::StartTracingDoneCallback());
   }
 
-  RunTestOnMainThreadLoop();
+  {
+    // 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();
+  }
 
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableTracing)) {