D3D11: Pass Context to more Image methods. Needed to get access to the scratch buffer. Bug: chromium:867089 Change-Id: I217bde149d24432e4baa276ead02ebc52a219958 Reviewed-on: https://chromium-review.googlesource.com/1149081 Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>