This ensures coverage is installed, rather than depending on it being
installed in your system.

BUG=671189

Change-Id: Id9d7c514b4db53963381c5269bee06c706b23751
Reviewed-on: https://chromium-review.googlesource.com/442050
Commit-Queue: Stephen Martinis <martiniss@chromium.org>
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>