Work around for use-after-free cert bug

Holds a strong references in the cert cache.
This is a simpler alternative to full backport of upstream fix,
from http://crrev.com/92977 -- see bug for more details.

BUG: 6508448

Change-Id: Ib47ca2e33b9e43ac47baf645069ecaab257ec74a
3 files changed