Lazily loading input layouts can also save memory and startup time.
There are several cases where we don't need these resources until
later, or sometimes, at all.

BUG=angleproject:1014

Change-Id: I4e0d45353b5d3969bd1ed86ad26f47d34e542ed5
Reviewed-on: https://chromium-review.googlesource.com/282551Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>