From e6b4160be15d8a0f541b598280d1bb2f1d07a06c Mon Sep 17 00:00:00 2001
From: David Anderson <danderson@mozilla.com>
Date: Mon, 20 Apr 2015 11:16:55 -0400
Subject: [PATCH] Fix a potential null-deref in
 TabChild::HandlePossibleViewportChange. (bug 1156156, r=kats)

--HG--
extra : rebase_source : 8dd897458121121c77442901fb728a53fc912ef8
---
 dom/ipc/TabChild.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/dom/ipc/TabChild.cpp b/dom/ipc/TabChild.cpp
index 97a09a06287b..461a1de6a072 100644
--- a/dom/ipc/TabChild.cpp
+++ b/dom/ipc/TabChild.cpp
@@ -275,6 +275,9 @@ TabChildBase::HandlePossibleViewportChange(const ScreenIntSize& aOldScreenSize)
     Stringify(aOldScreenSize).c_str(), Stringify(mInnerSize).c_str());
 
   nsCOMPtr<nsIDocument> document(GetDocument());
+  if (!document) {
+    return false;
+  }
 
   nsViewportInfo viewportInfo = nsContentUtils::GetViewportInfo(document, mInnerSize);
   uint32_t presShellId = 0;