Disable history API on YouTube in order to block ads in subsequent videos

safari/include.youtube.js

 /*
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 (function() {
   if (document.domain != "www.youtube.com")
     return;
 
+  pushStateDisabled = false;
+
   function rewriteFlashvars(flashvars)
   {
     var pairs = flashvars.split("&");
     for (var i = 0; i < pairs.length; i++)
       if (/^((ad|afv|adsense|iv)(_.*)?|(ad3|iv3|st)_module|prerolls|interstitial|infringe|invideo)=/.test(pairs[i]))
         pairs.splice(i--, 1);
     return pairs.join("&");
   }
 
   function patchPlayer(player) 
@@ skipping 22 matching lines @@
         if (value != newValue)
         {
           param.setAttribute("value", newValue);
           flashvarsChanged = true;
         }
       }
     }
 
     if (flashvarsChanged)
       player.parentNode.replaceChild(newPlayer, player);
+
+    // if history.pushState is available, YouTube uses the history API
+    // when navigation from one video to another, and tells the flash
+    // player with JavaScript which video and which ads to show next,
+    // bypassing our flashvars rewrite code. So we disable
+    // history.pushState on pages with YouTube's flash player.
+    if (!pushStateDisabled)
+    {
+      var script = document.createElement("script");
+      script.type = "application/javascript";
+      script.textContent = "history.pushState = undefined;";
+      document.documentElement.appendChild(script);

[Wladimir Palant, 2014/02/24 13:15:03]

We shouldn't leave this script around, it needs to be removed once it did its
job. The other option would be running location.href =
"javascript:void(history.pushState = undefined);" - this shouldn't leave any
artifacts behind.

[Sebastian Noack, 2014/02/24 14:32:09]

Done.

+
+      pushStateDisabled = true;

[Wladimir Palant, 2014/02/24 13:15:03]

Why is this flag necessary? Content scripts should never run twice for the same
page.

[Sebastian Noack, 2014/02/24 14:32:09]

Yes, but the code runs per player loaded. However now where we don't add a
script tag anymore, I also got rid of that flag.

+    }
   }
 
   var deferred = [];
   function patchPlayerDeferred(player)
   {
     deferred.push(player);
   }
 
   var onBeforeLoadYoutubeVideo = patchPlayerDeferred;
   function onBeforeLoad(event)
   {
     if ((event.target.localName == "object" || event.target.localName == "embed") && /:\/\/[^\/]*\.ytimg\.com\//.test(event.url))
       onBeforeLoadYoutubeVideo(event.target);
   }
 
   ext.backgroundPage.sendMessage({type: "get-domain-enabled-state"}, function(response)
   {
     if (response.enabled)
     {
       deferred.forEach(patchPlayer);
       onBeforeLoadYoutubeVideo = patchPlayer;
     }
     else
       document.removeEventListener("beforeload", onBeforeLoad);
   });
 
   document.addEventListener("beforeload", onBeforeLoad, true);
 })();