remove deprecated SkBitmap::eraseRGB()

Change-Id: I1adf711d39f441154aa1c032d49583d0c45d2568
Reviewed-on: https://skia-review.googlesource.com/c/159482
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Cary Clark <caryclark@google.com>
2 files changed