Issue 5599 - Delay composer initialization if ext object is unavailable

composer.postload.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 461 matching lines @@
   }
   unhighlightElements();
 
   let overlays = document.getElementsByClassName("__adblockplus__overlay");
   while (overlays.length > 0)
     overlays[0].parentNode.removeChild(overlays[0]);
 
   ext.onExtensionUnloaded.removeListener(deactivateBlockElement);
 }
 
-if (document instanceof HTMLDocument)
+function initializeComposer()
 {
+  if (typeof ext == "undefined")
+    return false;
+
   // Use a contextmenu handler to save the last element the user right-clicked
   // on. To make things easier, we actually save the DOM event. We have to do
   // this because the contextMenu API only provides a URL, not the actual DOM
   // element.
   //   We also need to make sure that the previous right click event,
   // if there is one, is removed. We don't know which frame it is in so we must
   // send a message to the other frames to clear their old right click events.
   document.addEventListener("contextmenu", event =>
   {
     lastRightClickEvent = event;
     lastRightClickEventIsMostRecent = true;
 
     browser.runtime.sendMessage({
       type: "forward",
       payload:
       {
         type: "composer.content.clearPreviousRightClickEvent"
       }
     });
   }, true);
 
-  ext.onMessage.addListener((msg, sender, sendResponse) =>
+  ext.onMessage.addListener((message, sender, sendResponse) =>

[Manish Jethani, 2017/10/17 16:43:16]

Unrelated renaming.

   {
-    switch (msg.type)
+    switch (message.type)
     {
       case "composer.content.getState":
         if (window == window.top)
         {
           sendResponse({
             active: currentlyPickingElement || blockelementPopupId != null
           });
         }
         break;
       case "composer.content.startPickingElement":
         if (window == window.top)
           startPickingElement();
         break;
       case "composer.content.contextMenuClicked":
         let event = lastRightClickEvent;
         deactivateBlockElement();
         if (event)
         {
           getBlockableElementOrAncestor(event.target, element =>
           {
             if (element)
             {
               currentElement = element;
               elementPicked(event);
             }
           });
         }
         break;
       case "composer.content.finished":
-        if (currentElement && msg.remove)
+        if (currentElement && message.remove)
         {
           // Hide the selected element itself if an added blocking
           // filter is causing it to collapse. Note that this
           // behavior is incomplete, but the best we can do here,
           // e.g. if an added blocking filter matches other elements,
           // the effect won't be visible until the page is is reloaded.
           checkCollapse(currentElement.prisoner || currentElement);
 
           // Apply added element hiding filters.
           elemhide.apply();
         }
         deactivateBlockElement();
         break;
       case "composer.content.clearPreviousRightClickEvent":
         if (!lastRightClickEventIsMostRecent)
           lastRightClickEvent = null;
         lastRightClickEventIsMostRecent = false;
         break;
       case "composer.content.dialogOpened":
         if (window == window.top)
-          blockelementPopupId = msg.popupId;
+          blockelementPopupId = message.popupId;
         break;
       case "composer.content.dialogClosed":
         // The onRemoved hook for the popup can create a race condition, so we
         // to be careful here. (This is not perfect, but best we can do.)
-        if (window == window.top && blockelementPopupId == msg.popupId)
+        if (window == window.top && blockelementPopupId == message.popupId)
         {
           browser.runtime.sendMessage({
             type: "forward",
             payload:
             {
               type: "composer.content.finished"
             }
           });
         }
         break;
     }
   });
 
   if (window == window.top)
     browser.runtime.sendMessage({type: "composer.ready"});
+
+  return true;
 }
+
+if (document instanceof HTMLDocument)
+{
+  // There's a bug in Firefox that causes document_end content scripts to run
+  // before document_start content scripts on extension startup. In this case
+  // the ext object is undefined, we fail to initialize, and initializeComposer
+  // returns false. As a workaround, try again after a timeout.
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=1395287
+  if (!initializeComposer())
+    setTimeout(initializeComposer, 2000);

[Manish Jethani, 2017/10/17 16:43:16]

Two seconds is probably fine.

+}