Rename fillRectWithLocalMatrix -> fillPixelsWithLocalMatrix

Rounding out to pixel grid boundaries makes this method dmsaa-ready by
ensuring no pixels have partial msaa sample coverage.

Bug: skia:11396
Change-Id: I2543c8806f94692992a692bd5adedf41326c8910
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/383416
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
4 files changed