Migrate MessageLoop::ScopedNestableTaskAllower to...

Migrate MessageLoop::ScopedNestableTaskAllower to RunLoop::Type::kNestableTasksAllowed in /content/browser/site_per_process_browsertest.cc

This is another scripted pass done by a slightly modified version of
https://bugs.chromium.org/p/chromium/issues/detail?id=781352#c1 which
has a better notion of "scope".

The script should have replaced a MessageLoop::ScopedNestableTaskAllower
in the same scope as a RunLoop with a RunLoop of
Type::kNestableTasksAllowed.

Includes should have been stripped if that was the last usage of message_loop.h
in that file.

Please CQ if LGTY

This CL was uploaded by git cl split.

R=kenrb@chromium.org

Bug: 781352
Change-Id: Ie0c1d1908812adc327f0777d552c7e4c97433d80
Reviewed-on: https://chromium-review.googlesource.com/1014781
Commit-Queue: Ken Buchanan <kenrb@chromium.org>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551323}

content/browser/site_per_process_browsertest.cc

@@ -10872,9 +10872,7 @@ class CommitMessageOrderReverser : public DidCommitProvisionalLoadInterceptor {
     if (params->url == deferred_url_) {
       std::move(deferred_url_triggered_action_).Run(render_frame_host);
 
-      base::MessageLoop::ScopedNestableTaskAllower allow(
-          base::MessageLoop::current());
-      base::RunLoop nested_run_loop;
+      base::RunLoop nested_run_loop(base::RunLoop::Type::kNestableTasksAllowed);
       nested_loop_quit_ = nested_run_loop.QuitClosure();
       nested_run_loop.Run();
       outer_run_loop.Quit();