From 9cd57f47997a8905e7b937ae75bc794c4d23dd02 Mon Sep 17 00:00:00 2001
From: Justin Lebar <justin.lebar@gmail.com>
Date: Wed, 31 Oct 2012 15:19:18 -0400
Subject: [PATCH] Bug 805207 - Follow-up: Add guard so KillClearOnShutdown
 doesn't crash if we haven't ClearOnShutdown'ed any objects. r=me, landed on a
 CLOSED TREE

---
 xpcom/base/ClearOnShutdown.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/xpcom/base/ClearOnShutdown.h b/xpcom/base/ClearOnShutdown.h
index fb9bf1cc7234..4bc4aaaa0865 100644
--- a/xpcom/base/ClearOnShutdown.h
+++ b/xpcom/base/ClearOnShutdown.h
@@ -91,10 +91,12 @@ inline void KillClearOnShutdown()
 
   MOZ_ASSERT(NS_IsMainThread());
 
-  ShutdownObserver *observer;
-  while ((observer = sShutdownObservers->popFirst())) {
-    observer->Shutdown();
-    delete observer;
+  if (sShutdownObservers) {
+    ShutdownObserver *observer;
+    while ((observer = sShutdownObservers->popFirst())) {
+      observer->Shutdown();
+      delete observer;
+    }
   }
 
   sShutdownObservers = nullptr;