Push setMipColorMode calls further down-stack & add to GrTextureProxy

setMipColorMode seems like an odd call. 

Change-Id: I24a1ac3883d52499f3be27282d006144d15b26f1
Reviewed-on: https://skia-review.googlesource.com/9725
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
9 files changed