LayerAnimator must be prepared for its owning layer's deletion whenever it notifies observers.

ui/compositor/layer.cc

Index: ui/compositor/layer.cc
diff --git a/ui/compositor/layer.cc b/ui/compositor/layer.cc
index 7e7964900876cb70a32b835c53a83ef05d51e087..71daa33f74c9af71352b6bd8f0ed44a8292b9412 100644
--- a/ui/compositor/layer.cc
+++ b/ui/compositor/layer.cc
@@ -95,7 +95,9 @@ Layer::~Layer() {
   // Destroying the animator may cause observers to use the layer (and
   // indirectly the WebLayer). Destroy the animator first so that the WebLayer
   // is still around.
-  animator_.reset();
+  if (animator_)
+    animator_->SetDelegate(NULL);
+  animator_ = NULL;
   if (compositor_)
     compositor_->SetRootLayer(NULL);
   if (parent_)
@@ -174,7 +176,7 @@ bool Layer::Contains(const Layer* other) const {
 void Layer::SetAnimator(LayerAnimator* animator) {
   if (animator)
     animator->SetDelegate(this);
-  animator_.reset(animator);
+  animator_ = animator;
 }
 
 LayerAnimator* Layer::GetAnimator() {