From 56064db6ce8e22ce2ceca81b4f9833f8bd604a08 Mon Sep 17 00:00:00 2001
From: Boris Zbarsky <bzbarsky@mit.edu>
Date: Fri, 12 Feb 2016 21:29:49 -0500
Subject: [PATCH] Bug 1247872.  Just get our private browsing state directly
 off the docshells we already have instead of trying to indirect through their
 documents. r=smaug

---
 docshell/base/nsDocShell.cpp | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index b90661b2640..3df3473a3ca 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -3492,22 +3492,19 @@ nsDocShell::CanAccessItem(nsIDocShellTreeItem* aTargetItem,
 
   nsCOMPtr<nsIDocShell> targetDS = do_QueryInterface(aTargetItem);
   nsCOMPtr<nsIDocShell> accessingDS = do_QueryInterface(aAccessingItem);
-  if (!!targetDS != !!accessingDS) {
-    // We must be able to convert both or neither to nsIDocShell.
+  if (!targetDS || !accessingDS) {
+    // We must be able to convert both to nsIDocShell.
     return false;
   }
 
-  if (targetDS && accessingDS &&
-      (targetDS->GetIsInBrowserElement() !=
-         accessingDS->GetIsInBrowserElement() ||
-       targetDS->GetAppId() != accessingDS->GetAppId())) {
+  if (targetDS->GetIsInBrowserElement() != accessingDS->GetIsInBrowserElement() ||
+      targetDS->GetAppId() != accessingDS->GetAppId()) {
     return false;
   }
 
   // A private document can't access a non-private one, and vice versa.
-  if (aTargetItem->GetDocument()->GetLoadContext()->UsePrivateBrowsing() !=
-      aAccessingItem->GetDocument()->GetLoadContext()->UsePrivateBrowsing())
-  {
+  if (static_cast<nsDocShell*>(targetDS.get())->UsePrivateBrowsing() !=
+      static_cast<nsDocShell*>(accessingDS.get())->UsePrivateBrowsing()) {
     return false;
   }