GitLab

As a temporary measure, set crash keys before calling
CallbackBase::IsCancelled to see if there is any pattern among
the crashes.

Bug: 798554
Change-Id: I55fcba6b378abdbbd69531faeda91c7c19874eb6
Reviewed-on: https://chromium-review.googlesource.com/c/1257920
Commit-Queue: Alex Clarke <alexclarke@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596686}