ash: Remove aura dependencies from ash/system/web_notification

ash/shelf/shelf.h

Index: ash/shelf/shelf.h
diff --git a/ash/shelf/shelf.h b/ash/shelf/shelf.h
index a780fb3a7bb7c271f44c2341335ad666c7bff72f..f88dcd8136eac3918a9f88a9b9902d1aa553afdc 100644
--- a/ash/shelf/shelf.h
+++ b/ash/shelf/shelf.h
@@ -5,6 +5,8 @@
 #ifndef ASH_SHELF_SHELF_H_
 #define ASH_SHELF_SHELF_H_
 
+#include <stdint.h>
+
 #include <memory>
 
 #include "ash/ash_export.h"
@@ -66,6 +68,10 @@ class ASH_EXPORT Shelf {
   // user is logged in yet.
   static Shelf* ForWindow(const aura::Window* window);
 
+  // Returns the shelf for the display with |display_id| or null if that display
+  // does not exist or does not have a shelf.
+  static Shelf* ForDisplayId(int64_t display_id);
+
   void SetAlignment(wm::ShelfAlignment alignment);
   wm::ShelfAlignment alignment() const { return alignment_; }
   bool IsHorizontalAlignment() const;