From a7bf9ca8586e16b25860fd4d18faf5658f44906e Mon Sep 17 00:00:00 2001
From: Josh Matthews <josh@joshmatthews.net>
Date: Tue, 21 Dec 2010 13:28:45 -0800
Subject: [PATCH] Bug 612551 - Clear appshell observers on xpcom-shutdown.
 r=blassey a=blocking-fennec

---
 widget/src/android/nsAppShell.cpp | 20 ++++++++++++++++++++
 widget/src/android/nsAppShell.h   |  3 +++
 2 files changed, 23 insertions(+)

diff --git a/widget/src/android/nsAppShell.cpp b/widget/src/android/nsAppShell.cpp
index 02f2290f83c9..8aa1a1f7d014 100644
--- a/widget/src/android/nsAppShell.cpp
+++ b/widget/src/android/nsAppShell.cpp
@@ -75,6 +75,8 @@ nsIGeolocationUpdate *gLocationCallback = nsnull;
 
 nsAppShell *nsAppShell::gAppShell = nsnull;
 
+NS_IMPL_ISUPPORTS_INHERITED1(nsAppShell, nsBaseAppShell, nsIObserver)
+
 nsAppShell::nsAppShell()
     : mQueueLock(nsnull),
       mCondLock(nsnull),
@@ -114,9 +116,27 @@ nsAppShell::Init()
     nsresult rv = nsBaseAppShell::Init();
     if (AndroidBridge::Bridge())
         AndroidBridge::Bridge()->NotifyAppShellReady();
+
+    nsCOMPtr<nsIObserverService> obsServ =
+            mozilla::services::GetObserverService();
+    if (obsServ) {
+        obsServ->AddObserver(this, "xpcom-shutdown", PR_FALSE);
+    }
     return rv;
 }
 
+NS_IMETHODIMP
+nsAppShell::Observe(nsISupports* aSubject,
+                    const char* aTopic,
+                    const PRUnichar* aData)
+{
+    if (!strcmp(aTopic, "xpcom-shutdown")) {
+        // We need to ensure no observers stick around after XPCOM shuts down
+        // or we'll see crashes, as the app shell outlives XPConnect.
+        mObserversHash.Clear();
+    }
+    return nsBaseAppShell::Observe(aSubject, aTopic, aData);
+}
 
 void
 nsAppShell::ScheduleNativeEventCallback()
diff --git a/widget/src/android/nsAppShell.h b/widget/src/android/nsAppShell.h
index 3a8f24cdb15a..5ddc08283ba1 100644
--- a/widget/src/android/nsAppShell.h
+++ b/widget/src/android/nsAppShell.h
@@ -61,6 +61,9 @@ public:
 
     nsAppShell();
 
+    NS_DECL_ISUPPORTS_INHERITED
+    NS_DECL_NSIOBSERVER
+
     nsresult Init();
 
     void NotifyNativeEvent();