Issue 6496 - Account for browsers that don't support notifications with buttons

lib/subscriptionInit.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 115 matching lines @@
         {
           selectedItem = subscription;
           selectedPrefix = prefix;
         }
       }
     }
   }
   return selectedItem;
 }
 
+function supportsNotificationsWithButtons()
+{
+  // Microsoft Edge (as of EdgeHTML 16) doesn't have the notifications API.
+  // Opera gives an asynchronous error when buttons are provided (we cannot
+  // detect that behavior without attempting to show a notification).
+  if (!("notifications" in browser) || info.application == "opera")
+    return false;
+
+  // Firefox throws synchronously if the "buttons" option is provided.
+  // If buttons are supported (i.e. on Chrome), this fails with
+  // a different error message due to missing required options.
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=1190681
+  try
+  {
+    browser.notifications.create({buttons: []});
+  }
+  catch (e)
+  {
+    if (e.toString().includes('"buttons" is unsupported'))
+      return false;
+  }
+
+  return true;
+}
+
 /**
  * Gets the filter subscriptions to be added when the extnesion is loaded.
  *
  * @return {Promise|Subscription[]}
  */
 function getSubscriptions()
 {
   let subscriptions = [];
 
   // Add pre-configured subscriptions
   for (let url of Prefs.additional_subscriptions)
     subscriptions.push(Subscription.fromURL(url));
 
   // Add "acceptable ads" and "anti-adblock messages" subscriptions
   if (firstRun)
   {
     let acceptableAdsSubscription = Subscription.fromURL(
       Prefs.subscriptions_exceptionsurl
     );
     acceptableAdsSubscription.title = "Allow non-intrusive advertising";
     subscriptions.push(acceptableAdsSubscription);
 
-    let antiAdblockSubscription = Subscription.fromURL(
-      Prefs.subscriptions_antiadblockurl
-    );
-    antiAdblockSubscription.disabled = true;
-    subscriptions.push(antiAdblockSubscription);
+    // Only add the anti-adblock messages subscription if
+    // the related notification can be shown on this browser.
+    if (supportsNotificationsWithButtons())
+    {
+      let antiAdblockSubscription = Subscription.fromURL(
+        Prefs.subscriptions_antiadblockurl
+      );
+      antiAdblockSubscription.disabled = true;
+      subscriptions.push(antiAdblockSubscription);
+    }
   }
 
   // Add default ad blocking subscription (e.g. EasyList)
   if (shouldAddDefaultSubscription())
   {
     return fetch("subscriptions.xml")
       .then(response => response.text())
       .then(text =>
       {
         let doc = new DOMParser().parseFromString(text, "application/xml");
@@ skipping 79 matching lines @@
  * Sets a callback that is called with an array of subscriptions to be added
  * during initialization. The callback must return an array of subscriptions
  * that will effectively be added.
  *
  * @param {function} callback
  */
 exports.setSubscriptionsCallback = callback =>
 {
   subscriptionsCallback = callback;
 };