Remove unused accessibility IPC.

It appears that AccessibilityMsg_HitTest is no longer used, having been
replaced by calling AccessibilityMsg_PerformAction with an action of
Action::kHitTest.

Bug: 977381
Change-Id: I888cb1767ab5a3fb85e6fdb17f895cee25e87b5f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1674344
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672044}
2 files changed