Keep dedicated layers for hiding animation

ui/views/corewm/window_animations.h

Index: ui/views/corewm/window_animations.h
diff --git a/ui/views/corewm/window_animations.h b/ui/views/corewm/window_animations.h
index f5728e6add64fc4ad60b8244540c8c6c28efec62..53c12712d2357df935ddc5314e3cea5193fd8df2 100644
--- a/ui/views/corewm/window_animations.h
+++ b/ui/views/corewm/window_animations.h
@@ -7,6 +7,7 @@
 
 #include <vector>
 
+#include "base/memory/scoped_ptr.h"
 #include "ui/views/views_export.h"
 
 namespace aura {
@@ -22,6 +23,7 @@ namespace ui {
 class ImplicitAnimationObserver;
 class Layer;
 class LayerAnimationSequence;
+class ScopedLayerAnimationSettings;
 }
 
 namespace views {
@@ -81,12 +83,33 @@ VIEWS_EXPORT void SetWindowVisibilityAnimationVerticalPosition(
     aura::Window* window,
     float position);
 
-// Creates an ImplicitAnimationObserver that takes ownership of the layers
-// associated with a Window so that the animation can continue after the Window
-// has been destroyed.
-// The returned object deletes itself when the animations are done.
-VIEWS_EXPORT ui::ImplicitAnimationObserver* CreateHidingWindowAnimationObserver(
-    aura::Window* window);
+
+// A scoped object which detaches the current layers which will animate and
+// recreates new layers for the window. Layers are owned by the animation
+// observer that is added to the deteached layer's animator, and will be deleted
+// when the animation is completed.
+class LayerDetacherForHidingAnimation {
+ public:
+  LayerDetacherForHidingAnimation() {}
+  virtual ~LayerDetacherForHidingAnimation() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(LayerDetacherForHidingAnimation);
+};
+
+// This has to be called before applying animations to |settings| because

[sky, 2014/03/10 13:30:40]

Is there anyway to this has been called before applying animations?

[oshima, 2014/03/10 17:48:24]

Not sure if I understood your question correctly.
If you change the properties on layers, it's too late to call this because the
animation is already scheduled by the |settings| and you can't observer them.

+// this will install animation observer.

[sky, 2014/03/10 13:30:40]

an animation observer

[oshima, 2014/03/10 17:48:24]

Done.

+VIEWS_EXPORT scoped_ptr<LayerDetacherForHidingAnimation>
+    DetachAndRecreateLayersForHidingAnimation(
+        aura::Window* window,
+        ui::ScopedLayerAnimationSettings* settings);
+
+// This installs a window observer that takes ownership of the layers
+// associated with a |winddow| so that the hiding animation can continue

[sky, 2014/03/10 13:30:40]

'a |winddow|' -> "window"

[oshima, 2014/03/10 17:48:24]

Done.

+// after the window has been destroyed.
+VIEWS_EXPORT void DetachLayersForHidingAnimationWhenDestroyed(
+    aura::Window* window,
+    ui::ScopedLayerAnimationSettings* settings);
 
 // Returns false if the |window| didn't animate.
 VIEWS_EXPORT bool AnimateOnChildWindowVisibilityChanged(aura::Window* window,