GitLab

CL:2261179 added a definition of this API, but there was no
implementation for it.
This CL adds it.

Bug: 1127721
Test: browser_test AccessibilityFeaturesApiTest
Change-Id: I131406370e6e81599286bb02b5dd3e0dd6761aef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2407937
Commit-Queue: Hiroki Sato <hirokisato@chromium.org>
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811488}