Issue 6692 - Update frame structure for about:blank 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 256 matching lines @@
     // update the state of the same document twice, otherewise the number
     // of any ads blocked already and any recorded sitekey could get lost.
     let frame = ext.getFrame(details.tabId, details.frameId);
     if (!frame || frame.url.href != details.url)
     {
       updatePageFrameStructure(details.frameId, details.tabId, details.url,
                                details.parentFrameId);
     }
   });
 
+  browser.webNavigation.onBeforeNavigate.addListener(details =>
+  {
+    // We also need to update the frame structure for about:blank frames, in
+    // order to properly attribute the requests they make.

[Sebastian Noack, 2018/05/29 17:35:09]

This comment is a bit vague. In my tests about:blank frames are handled by
onCommitted, but as it seems too late (i.e. after some sub-requests might
already have been sent).

[kzar, 2018/05/29 17:46:18]

Done.

+    let {url} = details;

[Sebastian Noack, 2018/05/29 17:35:08]

Nit: I don't think this temporary variable is worth to define, it's only used
twice and the property name is quite short.

[kzar, 2018/05/29 17:46:18]

Done.

+    if (url == "about:blank")
+    {
+      updatePageFrameStructure(details.frameId, details.tabId, url,
+                               details.parentFrameId);
+    }
+  });
+
   function forgetTab(tabId)
   {
     ext.pages.onRemoved._dispatch(tabId);
 
     removeFromAllPageMaps(tabId);
     framesOfTabs.delete(tabId);
   }
 
   browser.tabs.onReplaced.addListener((addedTabId, removedTabId) =>
   {
@@ skipping 283 matching lines @@
           return frames.get(0) || null;
         }
       };
     }
 
     return ext.onMessage._dispatch(
       message, sender, sendResponse
     ).includes(true);
   });
 }