[ash-md] Animates overview shield in and out

ash/common/wm/overview/window_selector.h

Index: ash/common/wm/overview/window_selector.h
diff --git a/ash/common/wm/overview/window_selector.h b/ash/common/wm/overview/window_selector.h
index da17731ed2f13f3e72bb403b5326f3afaa4f3d9f..55311cb619029f39cbc608ecf4914d449ad76d27 100644
--- a/ash/common/wm/overview/window_selector.h
+++ b/ash/common/wm/overview/window_selector.h
@@ -67,6 +67,8 @@ class ASH_EXPORT WindowSelector : public display::DisplayObserver,
   // Called when |window| is about to get closed.
   void WindowClosing(WindowSelectorItem* window);
 
+  WindowSelectorDelegate* delegate() { return delegate_; }
+
   bool restoring_minimized_windows() const {
     return restoring_minimized_windows_;
   }