Use TimeDelta to represent time offsets in StartAnimationOnCompositor

The current API is using a double. It's more convenient to use a
base::TimeDelta which represents durations.

Bug: 737867
Change-Id: I5f7936af7e8597d27b7c2a2e14e20376365e7c7f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1981613
Reviewed-by: Robert Flack <flackr@chromium.org>
Reviewed-by: Kevin Ellis <kevers@chromium.org>
Commit-Queue: Sergio Villar <svillar@igalia.com>
Cr-Commit-Position: refs/heads/master@{#729755}
7 files changed