Issue 1983 - Dispatch onLoading event for prerendered pages

chrome/ext/background.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2015 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 84 matching lines @@
       {
         callback(tabs.map(function(tab)
         {
           return new Page(tab);
         }));
       });
     },
     onLoading: new ext._EventTarget()
   };
 
+  chrome.tabs.onUpdated.addListener(function(tabId, changeInfo, tab)
+  {
+    if (changeInfo.status == "loading")
+      ext.pages.onLoading._dispatch(new Page(tab));
+  });
+
   chrome.webNavigation.onBeforeNavigate.addListener(function(details)
   {
     if (details.frameId == 0)
     {
       ext._removeFromAllPageMaps(details.tabId);
-      ext.pages.onLoading._dispatch(new Page({id: details.tabId, url: details.url}));
+
+      chrome.tabs.get(details.tabId, function()
+      {
+        // If the tab is prerendered, chrome.tabs.get() sets
+        // chrome.runtime.lastError and we have to dispatch the onLoading event,
+        // since the onUpdated event isn't dispatched for prerendered tabs.
+        // However, we have to keep relying on the unUpdated event for tabs that
+        // are already visible. Otherwise browser action changes get overridden
+        // when Chrome automatically resets them on navigation.
+        if (chrome.runtime.lastError)
+        {
+          ext.pages.onLoading._dispatch(
+            new Page({
+              id: details.tabId,
+              url: details.url
+            })
+          );
+        }
+      });
     }
   });
 
   function forgetTab(tabId)
   {
     ext._removeFromAllPageMaps(tabId);
     delete framesOfTabs[tabId];
   }
 
   chrome.tabs.onReplaced.addListener(function(addedTabId, removedTabId)
@@ skipping 368 matching lines @@
             callback(new Page(tab));
         }
         else
         {
           ext.pages.open(optionsUrl, callback);
         }
       });
     });
   };
 })();