extensions: Use base::RunLoop instead of deprecated MessageLoop methods.

chrome/browser/extensions/startup_helper.cc

Index: chrome/browser/extensions/startup_helper.cc
diff --git a/chrome/browser/extensions/startup_helper.cc b/chrome/browser/extensions/startup_helper.cc
index e6f74a7c6e4eedd734dd81e187907ee6f4190df0..605a93194f687d206e44bcbfe085f1988246d548 100644
--- a/chrome/browser/extensions/startup_helper.cc
+++ b/chrome/browser/extensions/startup_helper.cc
@@ -293,10 +293,10 @@ bool StartupHelper::InstallFromWebstore(const CommandLine& cmd_line,
   }
 
   AppInstallHelper helper;
-  helper.BeginInstall(
-      profile, id, true, base::MessageLoop::QuitWhenIdleClosure());
+  base::RunLoop run_loop;
+  helper.BeginInstall(profile, id, true, run_loop.QuitClosure());
+  run_loop.Run();
 
-  base::MessageLoop::current()->Run();
   if (!helper.success())
     LOG(ERROR) << "InstallFromWebstore failed with error: " << helper.error();
   return helper.success();