Implement asynchronous mutation of animation worklets.

* Adds MutateAynchronously method to the mutator dispatcher.
* Adds tests for ansynchronous mutation.
* Stubs in API for notification of mutation state (pending/complete).

Note async mutations are not used outside of testing with the patch pending completion of the notification plumbing in a separate CL.

Bug: 791280
Change-Id: I91545306c71899945f797a641831257247849b86
Reviewed-by: Robert Flack <>
Reviewed-by: Majid Valipour <>
Commit-Queue: Kevin Ellis <>
Cr-Commit-Position: refs/heads/master@{#625199}
10 files changed