Use SkPMColor4f throughout clear APIs

Bug: skia:
Change-Id: I5386e27edbcf39233880d869841a6632ecb9416c
Reviewed-on: https://skia-review.googlesource.com/c/168261
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
41 files changed