GitLab

Move method to a utilitiy file, since it doesn't need to be defined
on the ChromeVox Next testing class.

Bug: N/A
Change-Id: I504be13fbaeb1012671102155b460d3cea256515
AX-Relnotes: N/A
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2461947
Commit-Queue: Akihiro Ota <akihiroota@chromium.org>
Reviewed-by: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815878}