Issue 6786 - Display the Safari App Extension migration page

background.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 44 matching lines @@
     targetPage = sender.page;
 
   if (targetPage)
   {
     msg.payload.sender = sender.page.id;
     if (msg.expectsResponse)
       return new Promise(targetPage.sendMessage.bind(targetPage, msg.payload));
     targetPage.sendMessage(msg.payload);
   }
 });
+
+// Display a page to explain to users of Safari 10 and higher that they need
+// to migrate to our Safari App extension, but only once the migration page
+// is online. If it's not online yet, retry in 24 hours.
+function showMigrationPageWhenReady()
+{
+  fetch("https://eyeo.to/adblockplus/safari-app-extension-migration", {method: "HEAD"})
+    .then(function(response)
+    {
+      if (response.ok)
+        ext.pages.open(response.url);
+      else
+        throw "";
+    })
+    .catch(function()
+    {
+      window.setTimeout(showMigrationPageWhenReady, 1000 * 60 * 60 * 24);
+    });
+}
+
+if (Services.vc.compare(require("info").applicationVersion, "10") >= 0)
+  showMigrationPageWhenReady();