Site Settings Desktop: Implement protocol handler section.

chrome/browser/resources/settings/site_settings/site_list.js

Index: chrome/browser/resources/settings/site_settings/site_list.js
diff --git a/chrome/browser/resources/settings/site_settings/site_list.js b/chrome/browser/resources/settings/site_settings/site_list.js
index 4c24964206ec390dd650bfa6982894233d3a2d57..3020f519716a74a72d8ff935112a28ccc1f6b276 100644
--- a/chrome/browser/resources/settings/site_settings/site_list.js
+++ b/chrome/browser/resources/settings/site_settings/site_list.js
@@ -243,6 +243,13 @@ Polymer({
   getAllSitesList_: function() {
     var promiseList = [];
     for (var type in settings.ContentSettingsTypes) {
+      if (settings.ContentSettingsTypes[type] ==
+          settings.ContentSettingsTypes.PROTOCOL_HANDLERS) {
+        // Protocol handlers don't have data stored the way all the other
+        // categories do.
+        continue;
+      }
+
       promiseList.push(
           this.browserProxy_.getExceptionList(
               settings.ContentSettingsTypes[type]));