Update media_app to XU51Rj4Z6rGjyl18zltueVUb6Cpv4ey2XrfMw4NzyacC CIPD package.

CIPD package: https://chrome-infra-packages.appspot.com/p/chromeos_internal/apps/media_app/app/+/XU51Rj4Z6rGjyl18zltueVUb6Cpv4ey2XrfMw4NzyacC

Release notes: http://go/media_app-x20/relnotes/Stable/media_app_202008170800_RC00.html

Bug: b/162308416, b/164234229, b/163002455

Cq-Include-Trybots: chrome/try:linux-chromeos-chrome
Change-Id: I402b531c1b951b31b62debc02b32ea75e5bd381d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2358725Reviewed-by: Patti <patricialor@chromium.org>
Commit-Queue: Trent Apted <tapted@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799044}

DEPS

@@ -1561,7 +1561,7 @@ deps = {
     'packages': [
       {
         'package': 'chromeos_internal/apps/media_app/app',
-        'version': 'tERUmejT2tSaTumq5zSy0ws4x3w3pAMkEcpgdkD5WTEC',
+        'version': 'XU51Rj4Z6rGjyl18zltueVUb6Cpv4ey2XrfMw4NzyacC',
       },
     ],
     'condition': 'checkout_chromeos and checkout_src_internal',