Reland "[BGPT] Let cc initialize animation states in property nodes"

This is a reland of 54b17c7e812cd7c961abb45b4f8bcc7e2b1bbe43

The original CL called MutatorHost::InitClientAnimationState()
before updating animations. The new CL calls it after updating
animations. Not sure why the original CL caused flakiness of
but the test is no longer flaky with this new CL.

Original change's description:
> [BGPT] Let cc initialize animation states in property nodes
> In this way, blink::PropertyTreeManager no longer needs to care about
> the animation states. Now we initialize and change the states from a
> single source to avoid duplicate code and inconsistency.
> Bug: 935770
> Change-Id: I7f98d66677f557213fd4559895e9c2069de196e7
> Reviewed-on:
> Commit-Queue: Xianzhu Wang <>
> Reviewed-by: Robert Flack <>
> Reviewed-by: Philip Rogers <>
> Cr-Commit-Position: refs/heads/master@{#640892},

Bug: 935770
Change-Id: Icd7ec59b9e5b95f2c268baf88732788cde5da9c6
Reviewed-by: Xianzhu Wang <>
Commit-Queue: Xianzhu Wang <>
Cr-Commit-Position: refs/heads/master@{#641098}
12 files changed