Add context option to disable mipmap support

This is desired for a short term memory improvement on low memory
devices.

Bug: chromium:1138979
Change-Id: I7df41a9c4d21b7a7f62b738e6358b36dd262f77d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/327345
Commit-Queue: Kyle Charbonneau <kylechar@chromium.org>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
3 files changed