Fix a leak in wm::AnimateOnChildWindowVisibilityChanged().

ui/wm/core/window_animations.cc

Index: ui/wm/core/window_animations.cc
diff --git a/ui/wm/core/window_animations.cc b/ui/wm/core/window_animations.cc
index a79db3a15d6c45a76d6cdb78a8e3e7dc2db5035a..e536eadc1c848cf9c2d3f028549f5b6d245a0742 100644
--- a/ui/wm/core/window_animations.cc
+++ b/ui/wm/core/window_animations.cc
@@ -58,7 +58,8 @@ const float kWindowAnimation_Vertical_TranslateY = 15.f;
 // The subclass will determine when the animation is completed.
 class HidingWindowAnimationObserverBase : public aura::WindowObserver {
  public:
-  HidingWindowAnimationObserverBase(aura::Window* window) : window_(window) {
+  explicit HidingWindowAnimationObserverBase(aura::Window* window)
+      : window_(window) {
     window_->AddObserver(this);
   }
   virtual ~HidingWindowAnimationObserverBase() {
@@ -396,31 +397,29 @@ class RotateHidingWindowAnimationObserver
     : public HidingWindowAnimationObserverBase,
       public ui::LayerAnimationObserver {
  public:
-  RotateHidingWindowAnimationObserver(aura::Window* window)
-      : HidingWindowAnimationObserverBase(window), last_sequence_(NULL) {}
+  explicit RotateHidingWindowAnimationObserver(aura::Window* window)
+      : HidingWindowAnimationObserverBase(window) {}
   virtual ~RotateHidingWindowAnimationObserver() {}
 
-  void set_last_sequence(ui::LayerAnimationSequence* last_sequence) {
-    last_sequence_ = last_sequence;
+  void SetLastSequence(ui::LayerAnimationSequence* sequence) {
+    DCHECK(sequence);
+    sequence->AddObserver(this);
+    DetachAndRecreateLayers();
   }
 
   // ui::LayerAnimationObserver:
   virtual void OnLayerAnimationEnded(
       ui::LayerAnimationSequence* sequence) OVERRIDE {
-    if (last_sequence_ == sequence)
-      OnAnimationCompleted();
+    OnAnimationCompleted();
   }
   virtual void OnLayerAnimationAborted(
       ui::LayerAnimationSequence* sequence) OVERRIDE {
-    if (last_sequence_ == sequence)
-      OnAnimationCompleted();
+    OnAnimationCompleted();
   }
   virtual void OnLayerAnimationScheduled(
       ui::LayerAnimationSequence* sequence) OVERRIDE {}
 
  private:
-  ui::LayerAnimationSequence* last_sequence_;
-
   DISALLOW_COPY_AND_ASSIGN(RotateHidingWindowAnimationObserver);
 };
 
@@ -481,11 +480,11 @@ void AddLayerAnimationsForRotate(aura::Window* window, bool show) {
           rotation.release(), duration));
   ui::LayerAnimationSequence* last_sequence =
       new ui::LayerAnimationSequence(transition.release());
+
+  if (observer)
+    observer->SetLastSequence(last_sequence);

[sky, 2014/07/09 20:32:12]

If you do this here, doesn't that mean the animation that is started on the next
line applies to the new layer and not the old?

[please use gerrit instead, 2014/07/09 20:53:55]

Hm, I think you're right. The problem I'm encountering is that 
DetachAndRecreateLayers() should be ran while the window still exists, but
before the animation sequence is finished. Unit tests finish animations
immediately, so DetachAndRecreateLayers() cannot be run after the next line. Do
you have any pointers on how to make unit tests finish animations only after 
AddLayerAnimationsForRotate exits?

+
   window->layer()->GetAnimator()->ScheduleAnimation(last_sequence);
-  if (observer) {
-    observer->set_last_sequence(last_sequence);
-    observer->DetachAndRecreateLayers();
-  }
 }
 
 void AnimateShowWindow_Rotate(aura::Window* window) {