From 03c19cb5bb60e9ff51c8ff4dfc552d5f68120f80 Mon Sep 17 00:00:00 2001
From: Cameron McCormack <cam@mcc.id.au>
Date: Tue, 15 Jan 2013 09:45:53 +1100
Subject: [PATCH] Bug 830214 - Avoid crashing when printing a document with
 many mozPrintCallback canvases. r=roc

--HG--
extra : rebase_source : 98ae3180cb36f040241ae0b6850485923afe4570
---
 layout/generic/nsSimplePageSequence.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/layout/generic/nsSimplePageSequence.cpp b/layout/generic/nsSimplePageSequence.cpp
index 536dbda114b..81ef275af78 100644
--- a/layout/generic/nsSimplePageSequence.cpp
+++ b/layout/generic/nsSimplePageSequence.cpp
@@ -633,6 +633,10 @@ nsSimplePageSequenceFrame::PrePrintNextPage(nsITimerCallback* aCallback, bool* a
              size
            );
 
+        if (!printSurface) {
+          continue;
+        }
+
         nsICanvasRenderingContextInternal* ctx = canvas->GetContextAtIndex(0);
 
         if (!ctx) {