Fix a leak in wm::AnimateOnChildWindowVisibilityChanged().

ui/wm/core/window_animations.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/wm/core/window_animations.h"
 
 #include <math.h>
 
 #include <algorithm>
 #include <vector>
@@ skipping 94 matching lines @@
         window_->parent()->layer()->StackAbove(
             layer_owner_->root(), topmost_transient_child->layer());
       }
     }
   }
 
  protected:
   // Invoked when the hiding animation is completed.  It will delete
   // 'this', and no operation should be made on this object after this
   // point.
   void OnAnimationCompleted() {

[sky, 2014/06/27 22:32:56]

I would have thought we end up here. What particular subclass gets created and
how come it doesn't invoke this?

     // Window may have been destroyed by this point.
     if (window_) {
       aura::client::AnimationHost* animation_host =
           aura::client::GetAnimationHost(window_);
       if (animation_host)
         animation_host->OnWindowHidingAnimationCompleted();
-      window_->RemoveObserver(this);
     }
     delete this;
   }
 
  private:
   // Invoked when the window is destroyed (or destroying).
   void WindowInvalid() {
     layer_owner_->root()->SuppressPaint();
-
-    window_->RemoveObserver(this);
-    window_ = NULL;
+    delete this;
   }
 
   aura::Window* window_;
 
   // The owner of detached layers.
   scoped_ptr<ui::LayerTreeOwner> layer_owner_;
 
   DISALLOW_COPY_AND_ASSIGN(HidingWindowAnimationObserverBase);
 };
 
@@ skipping 505 matching lines @@
 }
 
 bool WindowAnimationsDisabled(aura::Window* window) {
   return (!gfx::Animation::ShouldRenderRichAnimation() || (window &&
           window->GetProperty(aura::client::kAnimationsDisabledKey)) ||
       CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kWindowAnimationsDisabled));
 }
 
 }  // namespace wm