Issue 5965 - Handle edge case when searching for options page tab

lib/options.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 20 matching lines @@
   browser.tabs.query({}, tabs =>
   {
     // We find a tab ourselves because Edge has a bug when quering tabs with
     // extension URL protocol:
     // https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/8094141/
     // https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/8604703/
     // Firefox won't let us query for moz-extension:// pages either, though
     // starting with Firefox 56 an extension can query for its own URLs:
     // https://bugzilla.mozilla.org/show_bug.cgi?id=1271354
     let fullOptionsUrl = browser.extension.getURL(optionsUrl);
-    callback(tabs.find(element => element.url == fullOptionsUrl));
+    let optionsTab = tabs.find(tab => tab.url == fullOptionsUrl);
+    if (optionsTab)
+    {
+      callback(optionsTab);
+      return;
+    }
+
+    // Newly created tabs might have about:blank as their URL in Firefox rather
+    // than the final options page URL, we need to wait for those to finish
+    // loading.
+    let potentialOptionTabIds = new Set(
+      tabs.filter(tab => tab.url == "about:blank" && tab.status == "loading")
+          .map(tab => tab.id)
+    );
+    if (potentialOptionTabIds.size == 0)
+    {
+      callback();
+      return;
+    }
+    let removeListener;
+    let updateListener = (tabId, changeInfo, tab) =>
+    {
+      if (potentialOptionTabIds.has(tabId) &&
+          changeInfo.status == "complete")
+      {
+        potentialOptionTabIds.delete(tabId);
+        let urlMatches = tab.url == fullOptionsUrl;

[Wladimir Palant, 2017/11/23 11:37:12]

Nit: Variable names are supposed to be nouns, not verbs. urlMatch maybe?

[kzar, 2017/11/23 11:51:08]

Done. (It's quite nice in Clojure you can use symbols like "?" so you could have
a variable name url-matches?.)

+        if (urlMatches || potentialOptionTabIds.size == 0)
+        {
+          browser.tabs.onUpdated.removeListener(updateListener);
+          browser.tabs.onRemoved.removeListener(removeListener);
+          callback(urlMatches ? tab : undefined);
+        }
+      }
+    };
+    browser.tabs.onUpdated.addListener(updateListener);
+    removeListener = removedTabId =>
+    {
+      potentialOptionTabIds.delete(removedTabId);
+      if (potentialOptionTabIds.size == 0)
+      {
+        browser.tabs.onUpdated.removeListener(updateListener);
+        browser.tabs.onRemoved.removeListener(removeListener);
+        callback();
+      }
+    };
+    browser.tabs.onRemoved.addListener(removeListener);
   });
 }
 
 function returnShowOptionsCall(optionsTab, callback)
 {
   if (!callback)
     return;
 
   if (optionsTab)
   {
@@ skipping 91 matching lines @@
         args: [
           {
             host: getDecodedHostname(currentPage.url).replace(/^www\./, ""),
             whitelisted: !!checkWhitelisted(currentPage)
           }
         ]
       });
     });
   });
 });