Video Player : Fixed resource path

Fixed resource path for video player. It doesn't accept
chrome-untrusted://resources/ directly, hence we have to use a
relative path.

Bug: 1134833
Change-Id: I41e0cdeb6e4be9bdcd043f5982521ea5d411787c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2446464Reviewed-by: Min Qin <qinmin@chromium.org>
Commit-Queue: Shakti Sahu <shaktisahu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813529}

chrome/browser/resources/video_tutorials/video_player.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import {$} from 'chrome://resources/js/util.m.js';
+import {$} from '//resources/js/util.m.js';
 
 function onDocumentLoaded() {
   // Find out the video, image, and caption urls from the url params.