dmazzoni@, there are some indications that this is an issue for ChromeVox.

In a CL at https://chromium-review.googlesource.com/c/chromium/src/+/765172
There's a question for ya about whether this is reasonable to address soon-ish or whether there's a suggested workaround. Thanks!

I tried reproducing the issue on a local ToT ChromeOS on Linux build, and could not repro, see screencast (I am using mod+right to navigate).

Deleted: repro_fail.mp4 250 KB

	repro_fail.mp4 250 KB View Download

#5 Nice! was there a fix in ChromeVox?

I tried these revisions
c1acbc5f3785df50787c8af6aa40c49b45ce6431  # happened to be what I had locally

586e53d6346df3a6147cddcda897d210d666e2b3  # just updated

Both still show the problem using mod+right on a linux chromeos build.

Is this possibly just an issue in the linux chromeos build (and not on an actual chromeos build)?

This is chromeos only.

So, after further experimentation figured out that ChromeVox's behavior changes, if the user tabs to the toggle control once. Updated repro steps to make it clear (also see new screencast).

1) Load chrome://extensions, go to the details page for any extension.
2) Use mod+right to navigate through the elements. ChromeVox skips the toggle.
3) Use Tab key to navigate to the toggle once (happens at 00:10s in the screencast).
4) Use mod+right/left to navigate through the elements again. This time ChromeVox visits the toggle. Also possibly related the following NOTREACHED error is thrown in the terminal when this happens
[1:1:1114/140846.497717:ERROR:AXLayoutObject.cpp(1920)] NOTREACHED() hit.

Deleted: repro_again.mp4 182 KB

	repro_again.mp4 182 KB View Download

 --enable-features=MaterialDesignExtensions may be necessary to see MD extensions on ChromeOS.

FYI, after our discussion, I experimented with bypassing the ChromeVox issue by moving the tabindex attribute from within the cr-toggle's #container div, to cr-toggle itself, see https://chromium-review.googlesource.com/c/chromium/src/+/769670. This seems to fix the issue for me.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c6ab93113db47c6d9e304ebf228a7ce70a50099a

commit c6ab93113db47c6d9e304ebf228a7ce70a50099a
Author: dpapad <dpapad@chromium.org>
Date: Wed Nov 15 00:52:45 2017

WebUI: Make cr-toggle ChromeVox friendly by moving tabindex to host.

Specifying the tabindex attribute on the top-level element also matches
what paper-toggle-button does.

Bug:  779268 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I7abf6c9014d60c05f7ace21951e2838810479352
Reviewed-on: https://chromium-review.googlesource.com/769670
Reviewed-by: Dave Schuyler <dschuyler@chromium.org>
Reviewed-by: Hector Carmona <hcarmona@chromium.org>
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516528}
[modify] https://crrev.com/c6ab93113db47c6d9e304ebf228a7ce70a50099a/chrome/test/data/webui/cr_elements/cr_toggle_test.js
[modify] https://crrev.com/c6ab93113db47c6d9e304ebf228a7ce70a50099a/ui/webui/resources/cr_elements/cr_toggle/cr_toggle.html
[modify] https://crrev.com/c6ab93113db47c6d9e304ebf228a7ce70a50099a/ui/webui/resources/cr_elements/cr_toggle/cr_toggle.js

Marking this as fixed since it has been addressed for MD Extensions. There might still be something to be fixed in ChromeVox itself, and should be tracked by a separate bug if so.