Issue 6746 - Update frame structure for about:srcdoc frames earlier

ext/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 246 matching lines @@
                              details.parentFrameId);
   },
   {types: ["main_frame", "sub_frame"], urls: ["http://*/*", "https://*/*"]},
   ["responseHeaders"]);
 
   browser.webNavigation.onBeforeNavigate.addListener(details =>
   {
     // Requests can be made by about:blank frames before the frame's
     // onCommitted event has fired, so we update the frame structure
     // for those now.
-    if (details.url == "about:blank")
+    if (details.url.startsWith("about:"))
     {
       updatePageFrameStructure(details.frameId, details.tabId, details.url,
                                details.parentFrameId);
     }
   });
 
   browser.webNavigation.onCommitted.addListener(details =>
   {
     // We have to update the frame structure for documents that weren't
     // loaded over HTTP (including documents cached by Service Workers),
@@ skipping 304 matching lines @@
           return frames.get(0) || null;
         }
       };
     }
 
     return ext.onMessage._dispatch(
       message, sender, sendResponse
     ).includes(true);
   });
 }