Reland "Don't change mask format in generateImage."

This reverts commit 9603395183e86c0dddf783024ec917a701592dce.

Change-Id: I40d50398ade8d7f5db77efeccda0b88ae796cf36
Reviewed-on: https://skia-review.googlesource.com/c/174312
Auto-Submit: Ben Wagner <bungeman@google.com>
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Herb Derby <herb@google.com>
2 files changed