compositor/layer_animator: handle delegate removal in LayerAnimation::StopAnimating

ui/wm/core/window_animations_unittest.cc

Index: ui/wm/core/window_animations_unittest.cc
diff --git a/ui/wm/core/window_animations_unittest.cc b/ui/wm/core/window_animations_unittest.cc
index 095ea02d2635c325b3ffd86645065e5d7a2f2b03..84bd151d38b8e9d804397ae3a1b9be7b7718b03d 100644
--- a/ui/wm/core/window_animations_unittest.cc
+++ b/ui/wm/core/window_animations_unittest.cc
@@ -300,4 +300,21 @@ TEST_F(WindowAnimationsTest, RotateHideNoLeak) {
   animating_layer->GetAnimator()->StopAnimating();
 }
 
+// The rotation animation for hiding a window should not crash when terminated
+// by LayerAnimator::StopAnimating().
+TEST_F(WindowAnimationsTest, RotateHideNoCrash) {
+  ui::ScopedAnimationDurationScaleMode scale_mode(
+      ui::ScopedAnimationDurationScaleMode::FAST_DURATION);
+
+  scoped_ptr<aura::Window> window(aura::test::CreateTestWindowWithId(0, NULL));
+  ui::Layer* animating_layer = window->layer();
+  wm::SetWindowVisibilityAnimationType(window.get(),
+                                       WINDOW_VISIBILITY_ANIMATION_TYPE_ROTATE);
+  AnimateOnChildWindowVisibilityChanged(window.get(), true);
+  window->layer()->GetAnimator()->Step(base::TimeTicks::Now() +
+                                       base::TimeDelta::FromSeconds(5));
+  AnimateOnChildWindowVisibilityChanged(window.get(), false);
+  animating_layer->GetAnimator()->StopAnimating();
+}
+
 }  // namespace wm