Begin centralizing opList DAG

For incremental topological sorting to work we need a choke point for adding opLists and dependencies. This new class will be that choke point.

Change-Id: I47ad6aa20f99cd03cd7e051f977d146a96f1734b
Reviewed-on: https://skia-review.googlesource.com/150614
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
2 files changed