[ash-md] Corrects a crash when a window is destroyed after leaving overview

ash/common/wm/overview/window_selector_item.cc

 // Copyright 2013 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 "ash/common/wm/overview/window_selector_item.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "ash/common/material_design/material_design_controller.h"
@@ skipping 15 matching lines @@
 #include "base/auto_reset.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
 #include "grit/ash_resources.h"
 #include "grit/ash_strings.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/compositor/layer_animation_sequence.h"
 #include "ui/compositor/scoped_animation_duration_scale_mode.h"
+#include "ui/gfx/animation/slide_animation.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/color_utils.h"
 #include "ui/gfx/geometry/safe_integer_conversions.h"
 #include "ui/gfx/geometry/vector2d.h"
 #include "ui/gfx/paint_vector_icon.h"
 #include "ui/gfx/transform_util.h"
 #include "ui/gfx/vector_icons_public.h"
 #include "ui/strings/grit/ui_strings.h"
 #include "ui/views/background.h"
 #include "ui/views/border.h"
@@ skipping 144 matching lines @@
         item_window_(item_window),
         corner_radius_(corner_radius),
         initial_color_(background),
         target_color_(background),
         current_value_(0),
         layer_(nullptr),
         animation_(new gfx::SlideAnimation(this)) {}
 
   ~RoundedContainerView() override { StopObservingLayerAnimations(); }
 
-  void OnItemRestored() { item_ = nullptr; }
+  void OnItemRestored() {
+    item_ = nullptr;
+    item_window_ = nullptr;
+  }
 
   // Starts observing layer animations so that actions can be taken when
   // particular animations (opacity) complete. It should only be called once
   // when the initial fade in animation is started.
   void ObserveLayerAnimations(ui::Layer* layer) {
     DCHECK(!layer_);
     layer_ = layer;
     layer_->GetAnimator()->AddObserver(this);
   }
 
   // Stops observing layer animations
   void StopObservingLayerAnimations() {
     if (!layer_)
       return;
     layer_->GetAnimator()->RemoveObserver(this);
     layer_ = nullptr;
   }
 
+  // Used by tests to set animation state.
+  gfx::SlideAnimation* animation() { return animation_.get(); }
+
   void set_color(SkColor target_color) { target_color_ = target_color; }
 
   // Starts a color animation using |tween_type|. The animation will change the
   // color from |initial_color_| to |target_color_| over |duration| specified
   // in milliseconds.
   // This animation can start once the implicit layer fade-in opacity animation
   // is completed. It is used to transition color from the opaque original
   // window header color to |kLabelBackgroundColor| on entry into overview mode
   // and from |kLabelBackgroundColor| back to the original window header color
   // on exit from the overview mode.
@@ skipping 660 matching lines @@
   // overview mode is shut down.
   views::Widget* widget_ptr = widget.get();
   std::unique_ptr<CleanupAnimationObserver> observer(
       new CleanupAnimationObserver(std::move(widget)));
   animation_settings->AddObserver(observer.get());
   window_selector_->delegate()->AddDelayedAnimationObserver(
       std::move(observer));
   widget_ptr->SetOpacity(0.f);
 }
 
+gfx::SlideAnimation* WindowSelectorItem::GetBackgroundViewAnimation() {
+  return background_view_ ? background_view_->animation() : nullptr;
+}
+
 }  // namespace ash