From 3c0ed4577b4b1c432336d69c64bc1008d2a4c49f Mon Sep 17 00:00:00 2001
From: Kartikaya Gupta <kgupta@mozilla.com>
Date: Wed, 31 Jul 2013 08:53:17 -0400
Subject: [PATCH] Bug 890932 - Add a missing lock in
 AsyncPanZoomController::SendAsyncScrollEvent. r=BenWa

---
 gfx/layers/ipc/AsyncPanZoomController.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gfx/layers/ipc/AsyncPanZoomController.cpp b/gfx/layers/ipc/AsyncPanZoomController.cpp
index 653fbdbacd3a..19e20631bb39 100644
--- a/gfx/layers/ipc/AsyncPanZoomController.cpp
+++ b/gfx/layers/ipc/AsyncPanZoomController.cpp
@@ -1455,7 +1455,8 @@ void AsyncPanZoomController::SendAsyncScrollEvent() {
   CSSRect contentRect;
   CSSSize scrollableSize;
   {
-    // XXX bug 890932 - there should be a lock here. but it causes a deadlock.
+    ReentrantMonitorAutoEnter lock(mMonitor);
+
     scrollId = mFrameMetrics.mScrollId;
     scrollableSize = mFrameMetrics.mScrollableRect.Size();
     contentRect = mFrameMetrics.CalculateCompositedRectInCssPixels();