[MD Bookmarks] Add toasts.

chrome/test/data/webui/md_bookmarks/command_manager_test.js

Index: chrome/test/data/webui/md_bookmarks/command_manager_test.js
diff --git a/chrome/test/data/webui/md_bookmarks/command_manager_test.js b/chrome/test/data/webui/md_bookmarks/command_manager_test.js
index ca849ce810bdee2b40dd6ad73cded5d00b9bfc8c..bd9de7c7a522a7cc863f7346c683feb5d903752a 100644
--- a/chrome/test/data/webui/md_bookmarks/command_manager_test.js
+++ b/chrome/test/data/webui/md_bookmarks/command_manager_test.js
@@ -43,6 +43,8 @@ suite('<bookmarks-command-manager>', function() {
 
     commandManager = new TestCommandManager();
     replaceBody(commandManager);
+    document.body.appendChild(
+        document.createElement('bookmarks-toast-manager'));
 
     Polymer.dom.flush();
   });