Move stats code to new layer (with configurable list of timers)

Bug: skia:
Change-Id: I3ca5c8c7047309983018339ec7b71b9aea5ee786
Reviewed-on: https://skia-review.googlesource.com/86921
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
7 files changed