This class is an MRU cache for sized objects, like Textures or
Program binaries. It is based on the base::HashingMRUCache type,
and evicts objects automatically.

BUG=angleproject:2044

Change-Id: I83859a0388f984e872fb9209e4c9efbf5d6c93f1
Reviewed-on: https://chromium-review.googlesource.com/517380Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>