Attempt 2 at Fixes crash introduced @ 153047 (you can hit crash by maximizing a

ui/compositor/layer_animation_observer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/compositor/layer_animation_observer.h"
 
 #include "ui/compositor/layer_animation_sequence.h"
 
 namespace ui {
 
@@ skipping 38 matching lines @@
   if (attached_sequences_.find(sequence) != attached_sequences_.end())
     attached_sequences_.erase(sequence);
   if (send_notification)
     OnDetachedFromSequence(sequence);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // ImplicitAnimationObserver
 
 ImplicitAnimationObserver::ImplicitAnimationObserver()
-    : active_(false) {
+    : active_(false),
+      destroyed_(NULL) {
 }
 
-ImplicitAnimationObserver::~ImplicitAnimationObserver() {}
+ImplicitAnimationObserver::~ImplicitAnimationObserver() {
+  if (destroyed_)
+    *destroyed_ = true;
+}
 
 void ImplicitAnimationObserver::SetActive(bool active) {
   active_ = active;
   CheckCompleted();
 }
 
 void ImplicitAnimationObserver::StopObservingImplicitAnimations() {
   SetActive(false);
   StopObserving();
 }
 
 void ImplicitAnimationObserver::OnLayerAnimationEnded(
     LayerAnimationSequence* sequence) {
+  bool destroyed = false;
+  destroyed_ = &destroyed;
   sequence->RemoveObserver(this);
+  if (destroyed)
+    return;
+  destroyed_ = NULL;
   DCHECK(attached_sequences().find(sequence) == attached_sequences().end());
   CheckCompleted();
 }
 
 void ImplicitAnimationObserver::OnLayerAnimationAborted(
     LayerAnimationSequence* sequence) {
   sequence->RemoveObserver(this);
   DCHECK(attached_sequences().find(sequence) == attached_sequences().end());
   CheckCompleted();
 }
 
 void ImplicitAnimationObserver::OnLayerAnimationScheduled(
     LayerAnimationSequence* sequence) {
 }
 
 void ImplicitAnimationObserver::OnAttachedToSequence(
     LayerAnimationSequence* sequence) {
 }
 
 void ImplicitAnimationObserver::OnDetachedFromSequence(
     LayerAnimationSequence* sequence) {
   DCHECK(attached_sequences().find(sequence) == attached_sequences().end());
   CheckCompleted();
 }
 
 void ImplicitAnimationObserver::CheckCompleted() {
   if (active_ && attached_sequences().empty()) {
+    active_ = false;
     OnImplicitAnimationsCompleted();
-    active_ = false;
   }
 }
 
 }  // namespace ui