Compact layout mananger animates windows rather than the default container layer.

ash/wm/compact_layout_manager.h

Index: ash/wm/compact_layout_manager.h
diff --git a/ash/wm/compact_layout_manager.h b/ash/wm/compact_layout_manager.h
index 4d713b659cd56e4c07c4dad21fc8db325acfa8e0..2818f58aee3cb5a53e98883e8135340437b0775d 100644
--- a/ash/wm/compact_layout_manager.h
+++ b/ash/wm/compact_layout_manager.h
@@ -63,6 +63,9 @@ class ASH_EXPORT CompactLayoutManager : public BaseLayoutManager,
   // The underlying layer is translated to -|offset_x| position.
   void AnimateSlideTo(int offset_x);
 
+  // Returns true if there is a slide in progress.
+  bool AreWindowsAnimating() const;
+
   // Layout all browser windows currently in the window cycle list.
   // skip |skip_this_window| if we do not want the window to be laid out.
   void LayoutWindows(aura::Window* skip_this_window);