Bug 1589076 - Add dns suffix list to about:networking r=kershaw,fluent-reviewers

Differential Revision: https://phabricator.services.mozilla.com/D49432

--HG--
extra : moz-landing-system : lando

toolkit/content/aboutNetworking.js

@@ -88,6 +88,21 @@ function displaySockets(data) {
 }
 
 function displayDns(data) {
+  let suffixContent = document.getElementById("dns_suffix_content");
+  let suffixParent = suffixContent.parentNode;
+  let suffixes = [];
+  try {
+    suffixes = gNetLinkSvc.dnsSuffixList; // May throw
+  } catch (e) {}
+  let suffix_tbody = document.createElement("tbody");
+  suffix_tbody.id = "dns_suffix_content";
+  for (let suffix of suffixes) {
+    let row = document.createElement("tr");
+    row.appendChild(col(suffix));
+    suffix_tbody.appendChild(row);
+  }
+  suffixParent.replaceChild(suffix_tbody, suffixContent);
+
   let cont = document.getElementById("dns_content");
   let parent = cont.parentNode;
   let new_cont = document.createElement("tbody");

toolkit/content/aboutNetworking.xhtml

@@ -85,6 +85,15 @@
           </div>
 
           <div id="dns" class="tab" hidden="true">
+              <table>
+                  <thead>
+                      <tr>
+                          <th data-l10n-id="dnssuffix"/>
+                      </tr>
+                  </thead>
+                  <tbody id="dns_suffix_content" />
+              </table>
+              <br/><br/>
               <table>
                   <thead>
                       <tr>

toolkit/locales/en-US/toolkit/about/aboutNetworking.ftl

@@ -6,6 +6,7 @@ title = About Networking
 http = HTTP
 sockets = Sockets
 dns = DNS
+dnssuffix = DNS suffix
 websockets = WebSockets
 refresh = Refresh
 auto-refresh = Autorefresh every 3 seconds