Add support for implementing ShaderMode::kRepeat with MIPs in GrTextureEffect.

Change-Id: I12ea00b35967f13e81410c584e34b62eea6c2ffe
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/270445
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
3 files changed