GitLab

* DCHECK() about not calling mojo callbacks before they're destroyed

This happens when the user types more quickly than we can respond

* Holding backspace accidentally shows matches for last deleted char

This happens because when input is emptied, the UI immediately hides
the matches UI, but an asynchronous result from the autocomplete
"backend" returns right after, which renders a new result.

R=mahmadi@chromium.org

Bug: 1001761, 1001762
Change-Id: Ic18dd8c63e79d4fe2d1563134920725dc19daf97
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1790434Reviewed-by: Tommy Li <tommycli@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: Dan Beam <dbeam@chromium.org>
Auto-Submit: Dan Beam <dbeam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695816}