Add TiledDrawScheduler so we can concurrently draw and enque
(instead of finishing enque before draw). The highlight is that we can now
achieve 9x speedup compared to 5x in all our previous approaches
(including multi-picture draw).

The schedulers here are experimental. I'd like to move on to try initializing
once for each draw before further polishing and optimizing the schedule
mechanism.

Bug: skia:
Change-Id: Idc3d030d475af9645c24c5372ff62b9a402206cc
Reviewed-on: https://skia-review.googlesource.com/17826
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Yuqian Li <liyuqian@google.com>
4 files changed