The last sentence here should make this a P1. We can't continue the flow if a user clicks cancel.

I fixed the bug in a new CL: https://chromium-review.googlesource.com/c/chromium/src/+/1249574

I just sent it in for review.

That proposed fix was misguided because it removed the handling of the user pressing enter. The updated fix (https://chromium-review.googlesource.com/c/chromium/src/+/1252503) the uses keypress event handling borrowed loosely from ui/webui/resources/cr_elements/cr_dialog/cr_dialog.js because the change event doesn't seem to discriminate between sources of the change submission (i.e. can't discern whether the enter key was pressed).

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/da4a7dfb643a64d939b05f253c575528a304297e

commit da4a7dfb643a64d939b05f253c575528a304297e
Author: Jordy Greenblatt <jordynass@chromium.org>
Date: Fri Sep 28 21:23:27 2018

[CrOS MultiDevice] Fix Setup Flow bug causing spurious setup attempts

The bug was caused by the change event on the password text field
triggering the event 'user-submitted-password' which causes a forward
navigate attempt. This fails if the password is wrong (this causes the
'incorrect password' issue in the bug) and succeeds if the password is
correct (this causes the spurious flow continuation issue).

Bug:  884965 
Change-Id: I4ae9f9f9fd01901dacd9e69a216bdd3123eb9344
Reviewed-on: https://chromium-review.googlesource.com/1252503
Commit-Queue: Jordy Greenblatt <jordynass@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595219}
[modify] https://crrev.com/da4a7dfb643a64d939b05f253c575528a304297e/ui/webui/resources/cr_components/chromeos/multidevice_setup/password_page.html
[modify] https://crrev.com/da4a7dfb643a64d939b05f253c575528a304297e/ui/webui/resources/cr_components/chromeos/multidevice_setup/password_page.js

 Issue 890903  has been merged into this issue.