Add instrumentation for AppCache-related crash when S13nSW is enabled.

Bug: 857005
Change-Id: Ib94a898048dfaa68dfc68cbaafd181980432df9a
Reviewed-on: https://chromium-review.googlesource.com/1119740
Reviewed-by: Makoto Shimazu <shimazu@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571813}
4 files changed