reland -- Disable animations during aura tests.

ui/gfx/compositor/layer_animation_sequence.cc

Index: ui/gfx/compositor/layer_animation_sequence.cc
diff --git a/ui/gfx/compositor/layer_animation_sequence.cc b/ui/gfx/compositor/layer_animation_sequence.cc
index b5475ecfa727409c92c9a51e5752133f3faba5a7..56dee9269b08a40d0d374af9034cce8b9e91aa33 100644
--- a/ui/gfx/compositor/layer_animation_sequence.cc
+++ b/ui/gfx/compositor/layer_animation_sequence.cc
@@ -36,6 +36,9 @@ void LayerAnimationSequence::Progress(base::TimeDelta elapsed,
   if (elements_.empty())
     return;
 
+  // We are now animating.
+  is_animating_ = true;
+
   if (is_cyclic_ && duration_ > base::TimeDelta()) {
     // If delta = elapsed - last_start_ is huge, we can skip ahead by complete
     // loops to save time.