[ash-md] Adjusts animation of the selector after closing an overview item

ash/common/wm/overview/window_grid.h

Index: ash/common/wm/overview/window_grid.h
diff --git a/ash/common/wm/overview/window_grid.h b/ash/common/wm/overview/window_grid.h
index 9a3202713b1ca00068b75b07b4e43f7736490e9c..1a9b6232a1503d9955eb381376720c1f0b22687a 100644
--- a/ash/common/wm/overview/window_grid.h
+++ b/ash/common/wm/overview/window_grid.h
@@ -91,6 +91,9 @@ class ASH_EXPORT WindowGrid : public WmWindowObserver {
   // If |pattern| is empty, no item is dimmed.
   void FilterItems(const base::string16& pattern);
 
+  // Fades out selector widget to transparent opacity effectively hiding it.
+  void HideSelector();
+
   // Returns true if the grid has no more windows.
   bool empty() const { return window_list_.empty(); }