Avoiding double resize of maximized windows upon user switch due to showing and hiding of the shelf

ash/shelf/shelf_widget.h

Index: ash/shelf/shelf_widget.h
diff --git a/ash/shelf/shelf_widget.h b/ash/shelf/shelf_widget.h
index 8a2ccc671fb4d2651a0553d7ba348bef0f42639a..97cf7ff3c5de2f21bfdbff2f32927b7dfe420288 100644
--- a/ash/shelf/shelf_widget.h
+++ b/ash/shelf/shelf_widget.h
@@ -45,6 +45,11 @@ class ASH_EXPORT ShelfWidget : public views::Widget,
                            BackgroundAnimatorChangeType change_type);
   ShelfBackgroundType GetBackgroundType() const;
 
+  // Hide the shelf behind a black bar during e.g. a user transition when |hide|
+  // is true. The |animation_time_ms| will be used as animation duration.
+  void HideShelfBehindBlackBar(bool hide, int animation_time_ms);
+  bool IsShelfHiddenBehindBlackBar() const;
+
   // Causes shelf items to be slightly dimmed (e.g. when a window is maximized).
   void SetDimsShelf(bool dimming);
   bool GetDimsShelf() const;