DOMUI Prefs: Add a deletable item list type, and use it for startup pages.

chrome/browser/resources/options/add_startup_page_overlay.js

Index: chrome/browser/resources/options/add_startup_page_overlay.js
diff --git a/chrome/browser/resources/options/add_startup_page_overlay.js b/chrome/browser/resources/options/add_startup_page_overlay.js
index 36eacae17d440298d1d8ede496c0270421cb0d88..659ef3b150e6913464c6881c70ab933602a250c6 100644
--- a/chrome/browser/resources/options/add_startup_page_overlay.js
+++ b/chrome/browser/resources/options/add_startup_page_overlay.js
@@ -34,7 +34,7 @@ cr.define('options', function() {
       addForm.onreset = this.dismissOverlay_.bind(this);
       addForm.onsubmit =  function(e) {
         var urlField = $('addStartupPageURL');
-        BrowserOptions.addStartupPage(urlField.value);
+        StartupPageManager.addStartupPage(urlField.value);
 
         self.dismissOverlay_();
         return false;