Remove more dead app list code.

ui/app_list/app_list_item.h

Index: ui/app_list/app_list_item.h
diff --git a/ui/app_list/app_list_item.h b/ui/app_list/app_list_item.h
index f6b1893e18e2d698db3be02249782e850767392f..4f8d9ba5f9716f1e49d90fd6b5f0f1d07b0b7404 100644
--- a/ui/app_list/app_list_item.h
+++ b/ui/app_list/app_list_item.h
@@ -83,10 +83,6 @@ class APP_LIST_EXPORT AppListItem {
   // Returns the number of child items if it has any (e.g. is a folder) or 0.
   virtual size_t ChildItemCount() const;
 
-  // Called when the extension preference changed. Used by ExtensionAppItem
-  // to update icon overlays.
-  virtual void OnExtensionPreferenceChanged();
-
   // Utility functions for sync integration tests.
   virtual bool CompareForTest(const AppListItem* other) const;
   virtual std::string ToDebugString() const;