From 69b2819df212e6101fe9e0428e2f07be31384d46 Mon Sep 17 00:00:00 2001
From: Andrew McCreight <continuation@gmail.com>
Date: Fri, 30 Jan 2015 10:55:11 -0800
Subject: [PATCH] Bug 1124261, part 2 - Make NS_NewXBLEventHandler infallible.
 r=smaug

---
 dom/xbl/nsXBLEventHandler.cpp   | 18 +++++++-----------
 dom/xbl/nsXBLEventHandler.h     |  5 ++---
 dom/xbl/nsXBLPrototypeHandler.h |  3 +--
 3 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/dom/xbl/nsXBLEventHandler.cpp b/dom/xbl/nsXBLEventHandler.cpp
index 46cb8743b829..8d10a772bfd2 100644
--- a/dom/xbl/nsXBLEventHandler.cpp
+++ b/dom/xbl/nsXBLEventHandler.cpp
@@ -160,30 +160,26 @@ nsXBLKeyEventHandler::HandleEvent(nsIDOMEvent* aEvent)
 
 ///////////////////////////////////////////////////////////////////////////////////
 
-nsresult
+already_AddRefed<nsXBLEventHandler>
 NS_NewXBLEventHandler(nsXBLPrototypeHandler* aHandler,
-                      nsIAtom* aEventType,
-                      nsXBLEventHandler** aResult)
+                      nsIAtom* aEventType)
 {
+  nsRefPtr<nsXBLEventHandler> handler;
+
   switch (nsContentUtils::GetEventClassID(nsDependentAtomString(aEventType))) {
     case eDragEventClass:
     case eMouseEventClass:
     case eMouseScrollEventClass:
     case eWheelEventClass:
     case eSimpleGestureEventClass:
-      *aResult = new nsXBLMouseEventHandler(aHandler);
+      handler = new nsXBLMouseEventHandler(aHandler);
       break;
     default:
-      *aResult = new nsXBLEventHandler(aHandler);
+      handler = new nsXBLEventHandler(aHandler);
       break;
   }
 
-  if (!*aResult)
-    return NS_ERROR_OUT_OF_MEMORY;
-
-  NS_ADDREF(*aResult);
-
-  return NS_OK;
+  return handler.forget();
 }
 
 nsresult
diff --git a/dom/xbl/nsXBLEventHandler.h b/dom/xbl/nsXBLEventHandler.h
index 0ae2ffebc865..7e64e44af583 100644
--- a/dom/xbl/nsXBLEventHandler.h
+++ b/dom/xbl/nsXBLEventHandler.h
@@ -113,10 +113,9 @@ private:
   bool mUsingContentXBLScope;
 };
 
-nsresult
+already_AddRefed<nsXBLEventHandler>
 NS_NewXBLEventHandler(nsXBLPrototypeHandler* aHandler,
-                      nsIAtom* aEventType,
-                      nsXBLEventHandler** aResult);
+                      nsIAtom* aEventType);
 
 nsresult
 NS_NewXBLKeyEventHandler(nsIAtom* aEventType, uint8_t aPhase,
diff --git a/dom/xbl/nsXBLPrototypeHandler.h b/dom/xbl/nsXBLPrototypeHandler.h
index d293c237a5c6..c15456818523 100644
--- a/dom/xbl/nsXBLPrototypeHandler.h
+++ b/dom/xbl/nsXBLPrototypeHandler.h
@@ -132,8 +132,7 @@ public:
   nsXBLEventHandler* GetEventHandler()
   {
     if (!mHandler) {
-      NS_NewXBLEventHandler(this, mEventName, getter_AddRefs(mHandler));
-      // XXX Need to signal out of memory?
+      mHandler = NS_NewXBLEventHandler(this, mEventName);
     }
 
     return mHandler;