Keep dedicated layers for hiding animation

ash/wm/window_animations_unittest.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 "ash/wm/window_animations.h"
 
 #include "ash/shell_window_ids.h"
 #include "ash/test/ash_test_base.h"
 #include "ash/wm/window_state.h"
 #include "ash/wm/workspace_controller.h"
@@ skipping 183 matching lines @@
       // Expect duration from the inner scope
       EXPECT_EQ(50,
                 layer->GetAnimator()->GetTransitionDuration().InMilliseconds());
     }
     window->Show();
     layer->GetAnimator()->StopAnimating();
   }
 
   // Test that it is possible to lock transition duration
   {
+    // Update layer as minimizing will replace the window's layer.
+    layer = window->layer();
     ui::ScopedLayerAnimationSettings settings1(layer->GetAnimator());
     settings1.SetTransitionDuration(base::TimeDelta::FromMilliseconds(1000));
     // Duration is locked in outer scope.
     settings1.LockTransitionDuration();
     {
       ui::ScopedLayerAnimationSettings settings2(layer->GetAnimator());
       // Transition duration setting is ignored.
       settings2.SetTransitionDuration(base::TimeDelta::FromMilliseconds(50));
       wm::GetWindowState(window.get())->Minimize();
       EXPECT_TRUE(layer->GetAnimator()->is_animating());
       // Expect duration from the outer scope
       EXPECT_EQ(1000,
                 layer->GetAnimator()->GetTransitionDuration().InMilliseconds());
     }
     window->Show();
     layer->GetAnimator()->StopAnimating();
   }
 
   // Test that duration respects default.
   {
+    layer = window->layer();
     // Query default duration.
     MinimizeAnimationObserver observer(layer->GetAnimator());
     wm::GetWindowState(window.get())->Minimize();
     EXPECT_TRUE(layer->GetAnimator()->is_animating());
     base::TimeDelta default_duration(observer.duration());
     window->Show();
     layer->GetAnimator()->StopAnimating();
 
+    layer = window->layer();
     ui::ScopedLayerAnimationSettings settings(layer->GetAnimator());
     settings.LockTransitionDuration();
     // Setting transition duration is ignored since duration is locked
     settings.SetTransitionDuration(base::TimeDelta::FromMilliseconds(1000));
     wm::GetWindowState(window.get())->Minimize();
     EXPECT_TRUE(layer->GetAnimator()->is_animating());
     // Expect default duration (200ms for stock ash minimizing animation).
     EXPECT_EQ(default_duration.InMilliseconds(),
               layer->GetAnimator()->GetTransitionDuration().InMilliseconds());
     window->Show();
     layer->GetAnimator()->StopAnimating();
   }
 }
 
 }  // namespace ash