It's not specific to Views-based login screen.

I switched to the WebUI version, and the problem still exists.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/663ac7270ab72aefda38b1397109fa3282deadf6

commit 663ac7270ab72aefda38b1397109fa3282deadf6
Author: David Tseng <dtseng@chromium.org>
Date: Fri May 04 16:42:25 2018

Revert "mash: Move SpokenFeedbackEventRewriter to ash; add mojo delegate"

This reverts commit 55b083a66d242a8c7319a56184196af71354b88c.

Reason for revert:
https://bugs.chromium.org/p/chromium/issues/detail?id=839683#c1
As a guess, key events used to go to SpokenFeedbackEventRewriter then KeyboardDrivenEventRewriter.

Original change's description:
> mash: Move SpokenFeedbackEventRewriter to ash; add mojo delegate
>
> Move the rewriter files to ash, keep the delegate impl in chrome.
> Add a mojo interface for the delegate to receive and return events.
> Ash's controller creates the rewriter, Chrome sets the delegate.
>
> Move, expand, and refine the existing unit tests.
>
> Add TODOs to refine the rewriter/delegate/ChromeVox pattern.
> (the rewriter shouldn't pass events that will need to be reposted)
>
> This should allow Mash to support this rewriter in the future.
> (for now, Ash doesn't get Window Service events sent to Chrome)
>
> Bug: 647781
> Test: No regressions with ChromeVox spoken feedback on Chrome OS.
> Change-Id: I4f7805298156ab9463ca3110a1e957f922c6d82b
> Reviewed-on: https://chromium-review.googlesource.com/1038819
> Commit-Queue: Michael Wasserman <msw@chromium.org>
> Reviewed-by: Tom Sepez <tsepez@chromium.org>
> Reviewed-by: James Cook <jamescook@chromium.org>
> Reviewed-by: David Tseng <dtseng@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#555867}

TBR=jamescook@chromium.org,dmazzoni@chromium.org,msw@chromium.org,dtseng@chromium.org,tsepez@chromium.org


No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 647781,  839683 
Change-Id: I8103916c1df3013d093cc6cdeac5745b6cd051d0
Reviewed-on: https://chromium-review.googlesource.com/1044492
Reviewed-by: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556086}
[modify] https://crrev.com/663ac7270ab72aefda38b1397109fa3282deadf6/ash/BUILD.gn
[delete] https://crrev.com/71e82edb257d2c687861e79174bea4cd07b9b03f/ash/events/OWNERS
[modify] https://crrev.com/663ac7270ab72aefda38b1397109fa3282deadf6/ash/events/event_rewriter_controller.cc
[modify] https://crrev.com/663ac7270ab72aefda38b1397109fa3282deadf6/ash/events/event_rewriter_controller.h
[delete] https://crrev.com/71e82edb257d2c687861e79174bea4cd07b9b03f/ash/events/spoken_feedback_event_rewriter.cc
[delete] https://crrev.com/71e82edb257d2c687861e79174bea4cd07b9b03f/ash/events/spoken_feedback_event_rewriter.h
[delete] https://crrev.com/71e82edb257d2c687861e79174bea4cd07b9b03f/ash/events/spoken_feedback_event_rewriter_unittest.cc
[modify] https://crrev.com/663ac7270ab72aefda38b1397109fa3282deadf6/ash/public/interfaces/event_rewriter_controller.mojom
[modify] https://crrev.com/663ac7270ab72aefda38b1397109fa3282deadf6/chrome/browser/chromeos/BUILD.gn
[add] https://crrev.com/663ac7270ab72aefda38b1397109fa3282deadf6/chrome/browser/chromeos/accessibility/spoken_feedback_event_rewriter.cc
[add] https://crrev.com/663ac7270ab72aefda38b1397109fa3282deadf6/chrome/browser/chromeos/accessibility/spoken_feedback_event_rewriter.h
[delete] https://crrev.com/71e82edb257d2c687861e79174bea4cd07b9b03f/chrome/browser/chromeos/accessibility/spoken_feedback_event_rewriter_delegate.cc
[delete] https://crrev.com/71e82edb257d2c687861e79174bea4cd07b9b03f/chrome/browser/chromeos/accessibility/spoken_feedback_event_rewriter_delegate.h
[add] https://crrev.com/663ac7270ab72aefda38b1397109fa3282deadf6/chrome/browser/chromeos/accessibility/spoken_feedback_event_rewriter_unittest.cc
[modify] https://crrev.com/663ac7270ab72aefda38b1397109fa3282deadf6/chrome/browser/chromeos/chrome_browser_main_chromeos.cc
[modify] https://crrev.com/663ac7270ab72aefda38b1397109fa3282deadf6/chrome/browser/chromeos/chrome_browser_main_chromeos.h

Thanks for finding this and reverting, I'll fix this defect in the CL before re-landing. Marking fixed.