Revert of Add thread checking to RunLoop, deprecate MessageLoopRunner.

content/browser/loader/async_revalidation_manager_browsertest.cc

Index: content/browser/loader/async_revalidation_manager_browsertest.cc
diff --git a/content/browser/loader/async_revalidation_manager_browsertest.cc b/content/browser/loader/async_revalidation_manager_browsertest.cc
index 2a9b8c33b38508834add590b22714eb3ec2faf8e..2646222c750da4b527c9fd849be1d341c2ba7c40 100644
--- a/content/browser/loader/async_revalidation_manager_browsertest.cc
+++ b/content/browser/loader/async_revalidation_manager_browsertest.cc
@@ -90,10 +90,8 @@
 
     // The second time this handler is run is the async revalidation. Tests can
     // use this for synchronisation.
-    if (version == 2) {
-      BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
-                              run_loop_.QuitClosure());
-    }
+    if (version == 2)
+      run_loop_.Quit();
     return std::move(http_response);
   }