Update UI and catch executeScript errors now shown in Canary

go-back-with-backspace/pages/common.js

Index: go-back-with-backspace/pages/common.js
diff --git a/go-back-with-backspace/pages/common.js b/go-back-with-backspace/pages/common.js
index 9fb28c52b55789d3514c40c499cda60951205af7..d0e32e4d34ee62d9b1597a14fa1b0443db06c8d3 100644
--- a/go-back-with-backspace/pages/common.js
+++ b/go-back-with-backspace/pages/common.js
@@ -2,26 +2,35 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// Define the customary shorthand for getElementById.
+var $ = document.getElementById.bind(document);
+
 // Load strings from messages.json into the HTML page. Each element that needs
 // an internationalized string should have an 'i18n' property holding the
-// name of the message to be used.
-function LoadInternationalizedStrings() {
+// name of the message to be used. If the element instead has an 'i18n-alt'
+// property, that message will be used for the alt and title attributes of the
+// element (generally an image).
+function loadInternationalizedStrings() {
   var all = document.querySelectorAll('[i18n]');
+  for (var i = 0; i < all.length; ++i)
+    all[i].textContent = chrome.i18n.getMessage(all[i].getAttribute('i18n'));
+
+  all = document.querySelectorAll('[i18n-alt]');
   for (var i = 0; i < all.length; ++i) {
-    var i18n = all[i].getAttribute('i18n');
-    if (i18n)
-      all[i].textContent = chrome.i18n.getMessage(i18n);
+      var message = chrome.i18n.getMessage(all[i].getAttribute('i18n-alt'));
+      all[i].alt = message;
+      all[i].title = message;
   }
 }
 
 // Open a pre-filled email to send feedback to the extension developers. The
 // initial content of the email depends on whether the URL of the current page
 // is provided.
-function reportPage(url) {
+function sendFeedback(opt_url) {
   var subject = chrome.i18n.getMessage('reportSubject');
   var body = '';
-  if (url)
-    body = chrome.i18n.getMessage('reportBodyWithURL', url);
+  if (opt_url)
+    body = chrome.i18n.getMessage('reportBodyWithURL', opt_url);
   else
     body = chrome.i18n.getMessage('reportBody');
   var msg = 'mailto:gobackwithbackspace@google.com' +