I had spoken to someone on the PolyGerrit team a while back about this and they said it could be a low priority gerrit feature request to make this configurable per label.

It would be easier to do this via the Auto-Submit feature ( issue 631551 ) instead, because I already hide and replace the quick approve button there.

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/gerrit-plugins/chromium-behavior/+/a1f80ba7773335061d226fd75657c6370743e9cd

commit a1f80ba7773335061d226fd75657c6370743e9cd
Author: Ravi Mistry <rmistry@google.com>
Date: Thu Oct 18 12:38:23 2018

Show the quick approve button if the current user has not approved yet

Bug:  895835 
Change-Id: Ife9d1ea69e9df967ecbca820e31e421091722a4a
[modify] https://crrev.com/a1f80ba7773335061d226fd75657c6370743e9cd/src/main/resources/static/chromium-behavior.html

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/gerrit-plugins/chromium-behavior/+/8accf52ee8b4ddec45acb05800c745acdbd0ff1c

commit 8accf52ee8b4ddec45acb05800c745acdbd0ff1c
Author: Ravi Mistry <rmistry@google.com>
Date: Thu Oct 18 13:09:34 2018

Remove hardcoded Code-Review label value

Bug:  883001 , 895835 
Change-Id: I310e958eb16caeda86c7080b66cbf445b3cbd2d8
[modify] https://crrev.com/8accf52ee8b4ddec45acb05800c745acdbd0ff1c/src/main/resources/static/chromium-behavior.html

This is now live and appears to be working.

I looked at a change with a CR+1 vote in chromium-review where Auto-Submit is not yet enabled and did not see the quick approve button: https://chromium-review.googlesource.com/c/chromium/src/+/1296534

Then I looked at a change with a CR+1 vote where Auto-Submit is enabled and saw the quick approve button: https://chrome-internal-review.googlesource.com/c/chrome/tools/build/+/700197

Marking as fixed.