Plumbing mipmaps to the point of creation.

When creating a DeferredTextureImage we may create mipmaps.
Those mipmaps need to then be passed along for when the texture is
actually created.

R=bsalomon@google.com
BUG=578304
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2031273002

Review-Url: https://codereview.chromium.org/2031273002
5 files changed