reland: mash: Remove ChromeLauncherController's |id_to_item_controller_map_|.

chrome/browser/ui/ash/launcher/chrome_launcher_controller.h

Index: chrome/browser/ui/ash/launcher/chrome_launcher_controller.h
diff --git a/chrome/browser/ui/ash/launcher/chrome_launcher_controller.h b/chrome/browser/ui/ash/launcher/chrome_launcher_controller.h
index 5e84748f463ad06b6fc249cd7be0efa08bd44008..d23b354e5671a03c9f061328d001e101240e15ff 100644
--- a/chrome/browser/ui/ash/launcher/chrome_launcher_controller.h
+++ b/chrome/browser/ui/ash/launcher/chrome_launcher_controller.h
@@ -89,11 +89,6 @@ class ChromeLauncherController : public ash::mojom::ShelfObserver,
   // browsers shelf item if needed.
   virtual void SetItemStatus(ash::ShelfID id, ash::ShelfItemStatus status) = 0;
 
-  // Updates the delegate associated with id (which should be a shortcut).
-  virtual void SetShelfItemDelegate(
-      ash::ShelfID id,
-      std::unique_ptr<ash::ShelfItemDelegate> item_delegate) = 0;
-
   // Closes or unpins the shelf item.
   virtual void CloseLauncherItem(ash::ShelfID id) = 0;
 
@@ -202,9 +197,6 @@ class ChromeLauncherController : public ash::mojom::ShelfObserver,
   virtual BrowserShortcutLauncherItemController*
   GetBrowserShortcutLauncherItemController() = 0;
 
-  virtual ash::ShelfItemDelegate* GetShelfItemDelegate(
-      const ash::ShelfID id) = 0;
-
   // Check if the shelf visibility (location, visibility) will change with a new
   // user profile or not. However, since the full visibility calculation of the
   // shelf cannot be performed here, this is only a probability used for