GitLab

Ensure that strings received by accessibility_ui message handlers are not
longer than 5000 characters. This ensures that a bad actor cannot send a
long string as a filter and overwhelm the buffer.

Bug: 785493,959368
Change-Id: Idbf9cb5ce137fdc782370cba12ead9a542574854
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1829954
Commit-Queue: Abigail Klein <abigailbklein@google.com>
Reviewed-by: Nektarios Paisios <nektar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702934}