ccpr: Abstract the draws list in a separate class

Bug: skia:
Change-Id: I583c1bdc470e5830d041955d14b164fc00d5d014
Reviewed-on: https://skia-review.googlesource.com/129227
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
6 files changed