Code:    void Wait() {
    message_loop_runner_->Run();
    message_loop_runner_ = new MessageLoopRunner;
   }

Commit Message: If a page calls |window.focus()|, kick it out of fullscreen.

BUG=776418, 800056

Change-Id: I1880fe600e4814c073f247c43b1c1ac80c8fc017
Reviewed-on: https://chromium-review.googlesource.com/852378
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533790}
CWE ID: 
   void Wait() {
    run_loop_->Run();
    run_loop_ = std::make_unique<base::RunLoop>();
   }
