Reorganize to extract GPU main drawing code

This class pertaining to painting into the Painter files. Reduce
the number of includes used in SkGlyphRun.

Change-Id: Iae00d57c85079b91cc6672d1ba1d52556a7e299d
Reviewed-on: https://skia-review.googlesource.com/c/168266
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Herb Derby <herb@google.com>
5 files changed