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

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 96d05363617bb8094c43e5b43e16b27bfaff0cd6..a118b2a2f5b0c57f8aa382ce5ef0f655e38d0624 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -2740,17 +2740,12 @@ void LayerTreeHostImpl::AnimateLayers(base::TimeTicks monotonic_time) {
     return;
 
   TRACE_EVENT0("cc", "LayerTreeHostImpl::AnimateLayers");
-
-  // TODO(ajuma): http://crbug.com/178171 - Animations use double for monotonic
-  // time.
-  double monotonic_time_for_cc_animations =
-      (monotonic_time - base::TimeTicks()).InSecondsF();
   AnimationRegistrar::AnimationControllerMap copy =
       animation_registrar_->active_animation_controllers();
   for (AnimationRegistrar::AnimationControllerMap::iterator iter = copy.begin();
        iter != copy.end();
        ++iter)
-    (*iter).second->Animate(monotonic_time_for_cc_animations);
+    (*iter).second->Animate(monotonic_time);
 
   SetNeedsRedraw();
 }