remove legacy forward declares

Bug: skia:
Change-Id: Ie83cef8e47b27c3a59fe251b9c81dca7c4d15232
Reviewed-on: https://skia-review.googlesource.com/c/188820
Reviewed-by: Mike Reed <reed@google.com>
Auto-Submit: Mike Reed <reed@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>
1 file changed