Remove calls to deprecated MessageLoop methods in content.

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 8d22f496ff31989105eb91290a8bf3da4fb8f137..c6a3777c77391e6184529fae5a2770b23c9202da 100644
--- a/content/public/test/test_utils.cc
+++ b/content/public/test/test_utils.cc
@@ -189,8 +189,7 @@ std::unique_ptr<base::Value> ExecuteScriptAndGetValue(
   render_frame_host->ExecuteJavaScriptForTests(
       base::UTF8ToUTF16(script),
       base::Bind(&ScriptCallback::ResultCallback, base::Unretained(&observer)));
-  base::MessageLoop* loop = base::MessageLoop::current();
-  loop->Run();
+  base::RunLoop().Run();
   return observer.result();
 }