Change the return value of ShouldRenderRichAnimation() in MACOSX

the return value of this fucntion is always true on platforms other than
Windows. In MAC, It was also changed to determine the value of reduce_motion,
as was Windows.

Bug: 8944
Change-Id: Ie6de6e12f2afdf1a1c25fe2a2a33d3505768b6f5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1510694
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#639565}
2 files changed