Roll Help App from q6S1Q6V4_... to MixcfTPFs...

Release_Notes: http://go/help_app-x20/relnotes/Main/help_app_nightly_202011130600_RC00.html

https://chrome-infra-packages.appspot.com/p/chromeos_internal/apps/help_app/app/+/MixcfTPFsHokR735rFKmvn0Ctjeu1IlipdRyybXfstwC

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://skia-autoroll.corp.goog/r/help-app-chromium-autoroll
Please CC help-app@grotations.appspotmail.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/master/autoroll/README.md

Cq-Include-Trybots: luci.chrome.try:linux-chromeos-chrome
Bug: None
Tbr: help-app@grotations.appspotmail.com
Change-Id: Idfa903002d7d0dd64dbb58a2a58015f9951b908c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2537912Reviewed-by: chromium-internal-autoroll <chromium-internal-autoroll@skia-corp.google.com.iam.gserviceaccount.com>
Commit-Queue: chromium-internal-autoroll <chromium-internal-autoroll@skia-corp.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#827285}

DEPS

@@ -1586,7 +1586,7 @@ deps = {
     'packages': [
       {
         'package': 'chromeos_internal/apps/help_app/app',
-        'version': 'q6S1Q6V4_M64y2wv8AI6ZmwjOFY46EgVtPz9XcWJVRsC',
+        'version': 'MixcfTPFsHokR735rFKmvn0Ctjeu1IlipdRyybXfstwC',
       },
     ],
     'condition': 'checkout_chromeos and checkout_src_internal',