If the calling code releases the keyed mutex after the unbind then D3D will
unbind the SRV or RTV from the pipeline without notifying the cache. This
allows the SRV to be destroyed, which means that a subsequently-created SRV
could have the same address. This would cause the new SRV to not be correctly
bound to the pipeline if its slot is the same as the unbound SRV.

BUG=588000
Change-Id: I0ad1ba3706a6bcc1fee50745e6148c9b23e578f6
Reviewed-on: https://chromium-review.googlesource.com/328400Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: John Bauman <jbauman@chromium.org>