add wiki_page helper to url_builder

app/services/wiki_pages/base_service.rb

@@ -10,7 +10,8 @@ module WikiPages
         # DEPRECATED
         repository: @project.hook_attrs.slice(:name, :url, :description, :homepage)
       }
-      page_url = "#{Gitlab.config.gitlab.url}#{@project.wiki.wiki_base_path}/#{page.slug}"
+
+      page_url = Gitlab::UrlBuilder.new(:wiki_page).build(page)
       hook_data[:object_attributes].merge!(url: page_url, action: action)
       hook_data
     end

lib/gitlab/url_builder.rb

@@ -20,6 +20,8 @@ module Gitlab
         merge_request_url(object)
       when Note
         note_url
+      when WikiPage
+        wiki_page_url
       else
         raise NotImplementedError.new("No URL builder defined for #{object.class}")
       end
@@ -58,5 +60,9 @@ module Gitlab
         project_snippet_url(snippet, anchor: dom_id(object))
       end
     end
+
+    def wiki_page_url
+      "#{Gitlab.config.gitlab.url}#{object.wiki.wiki_base_path}/#{object.slug}"
+    end
   end
 end