CC::Animations should use TimeTicks & TimeDelta to represent time

ui/compositor/layer_animation_sequence.cc

Index: ui/compositor/layer_animation_sequence.cc
diff --git a/ui/compositor/layer_animation_sequence.cc b/ui/compositor/layer_animation_sequence.cc
index 94b664b74a3dd9a4ebfd3e5e23a2b3c3dc6accd5..31d09c94775c78d71a360ac6e1f080171f6b3afd 100644
--- a/ui/compositor/layer_animation_sequence.cc
+++ b/ui/compositor/layer_animation_sequence.cc
@@ -219,9 +219,7 @@ void LayerAnimationSequence::OnThreadedAnimationStarted(
   LayerAnimationElement::AnimatableProperty event_property =
       LayerAnimationElement::ToAnimatableProperty(event.target_property);
   DCHECK(element_properties & event_property);
-  elements_[current_index]->set_effective_start_time(
-      base::TimeTicks::FromInternalValue(
-          event.monotonic_time * base::Time::kMicrosecondsPerSecond));
+  elements_[current_index]->set_effective_start_time(event.monotonic_time);
 }
 
 void LayerAnimationSequence::OnScheduled() {