Initiate regeneration of mipmaps from proxy DAG land

This allows us to resolve all the textures before executing a command
buffer, rather than interrupting execution as is currently done in the
GL backend.

Change-Id: I998546b312d24cf47fc2c837e7c94fbf95571af0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/230636
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
15 files changed