Fix chrome://accessibility crash on Chrome OS

HandleAccessibilityRequestCallback crashes if the chromevox view does
not have an AXPlatformNodeDelegate. This fixes the crash by ignoring
views without delegates in that call.

Change-Id: Iadc20f60ed6c3b6c1f351628ab408ab283abe08f
Reviewed-on: https://chromium-review.googlesource.com/1150859
Commit-Queue: James Wallace-Lee <jamwalla@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578355}
1 file changed