A query helper method in Context and a validation helper
method reduce code redundancy quite a bit.

BUG=angle:565

Change-Id: I96b9ecc4614e7e31240e31594223e8b9636d22c2
Reviewed-on: https://chromium-review.googlesource.com/188201Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>