Removes frontWindow usage from the stream converter.

extensions/firefox/content/PdfStreamConverter.jsm

@@ -319,11 +319,9 @@ ChromeActions.prototype = {
     var extHelperAppSvc =
           Cc['@mozilla.org/uriloader/external-helper-app-service;1'].
              getService(Ci.nsIExternalHelperAppService);
-    var frontWindow = Cc['@mozilla.org/embedcomp/window-watcher;1'].
-                         getService(Ci.nsIWindowWatcher).activeWindow;
 
     var docIsPrivate = this.isInPrivateBrowsing();
-    var netChannel = createNewChannel(blobUri, frontWindow.document, null);
+    var netChannel = createNewChannel(blobUri, this.domWindow.document, null);
     if ('nsIPrivateBrowsingChannel' in Ci &&
         netChannel instanceof Ci.nsIPrivateBrowsingChannel) {
       netChannel.setPrivate(docIsPrivate);
@@ -359,10 +357,14 @@ ChromeActions.prototype = {
       var listener = {
         extListener: null,
         onStartRequest: function(aRequest, aContext) {
+          var loadContext = self.domWindow
+                                .QueryInterface(Ci.nsIInterfaceRequestor)
+                                .getInterface(Ci.nsIWebNavigation)
+                                .QueryInterface(Ci.nsILoadContext);
           this.extListener = extHelperAppSvc.doContent(
             (data.isAttachment ? 'application/octet-stream' :
                                  'application/pdf'),
-            aRequest, frontWindow, false);
+            aRequest, loadContext, false);
           this.extListener.onStartRequest(aRequest, aContext);
         },
         onStopRequest: function(aRequest, aContext, aStatusCode) {