Issue 3208 - Improve the approach used to detect pop-up URL

lib/contentPolicy.js

Index: lib/contentPolicy.js
===================================================================
--- a/lib/contentPolicy.js
+++ b/lib/contentPolicy.js
@@ -476,22 +476,25 @@ var PolicyImplementation =
         if (!Policy.processNode(subject.opener, subject.opener.document, Policy.type.POPUP, uri, false))
         {
           subject.stop();
           Utils.runAsync(() => subject.close());
         }
         else if (uri.spec == "about:blank")
         {
           // An about:blank pop-up most likely means that a load will be
-          // initiated synchronously. Set a flag for our "http-on-opening-request"
-          // handler.
-          this.expectingPopupLoad = true;
-          Utils.runAsync(function()
+          // initiated asynchronously. Wait for that.
+          Utils.runAsync(() =>
           {
-            this.expectingPopupLoad = false;
+            let channel = subject.QueryInterface(Ci.nsIInterfaceRequestor)
+                                 .getInterface(Ci.nsIDocShell)
+                                 .QueryInterface(Ci.nsIDocumentLoader)
+                                 .documentChannel;
+            if (channel)
+              this.observe(subject, topic, data, channel.URI);
           });
         }
         break;
       }
       case "http-on-opening-request":
       case "http-on-modify-request":
       {
         if (!(subject instanceof Ci.nsIHttpChannel))
@@ -500,28 +503,16 @@ var PolicyImplementation =
         if (this.previousRequest && subject.URI == this.previousRequest[0] &&
             subject instanceof Ci.nsIWritablePropertyBag)
         {
           // We just handled a content policy call for this request - associate
           // the data with the channel so that we can find it in case of a redirect.
           subject.setProperty("abpRequestType", this.previousRequest[1]);
           this.previousRequest = null;
         }
-
-        if (this.expectingPopupLoad)
-        {
-          let wnd = Utils.getRequestWindow(subject);
-          if (wnd && wnd.opener && wnd.location.href == "about:blank")
-          {
-            this.observe(wnd, "content-document-global-created", null, subject.URI);
-            if (subject instanceof Ci.nsIWritablePropertyBag)
-              subject.setProperty("abpRequestType", Policy.type.POPUP);
-          }
-        }
-
         break;
       }
     }
   },
 
   //
   // nsIChannelEventSink interface implementation
   //