use SkFontMetrics so we can deprecated the typedef

Bug: skia:
Change-Id: Icd40c042b0a8251bbd0b39dd3ee1a4634fff379f
Reviewed-on: https://skia-review.googlesource.com/c/170344
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
40 files changed