From 600ab9bfb99ebd4516ce83cdc1e4ade73c654f19 Mon Sep 17 00:00:00 2001
From: Ben Kelly <ben@wanderview.com>
Date: Thu, 30 Oct 2014 11:12:09 -0400
Subject: [PATCH] Bug 1091091: Support ErrorResult in Promise::MaybeReject().
 r=bz

---
 dom/bindings/ToJSValue.cpp | 14 ++++++++++++++
 dom/bindings/ToJSValue.h   |  8 ++++++++
 dom/promise/Promise.h      |  5 +++++
 3 files changed, 27 insertions(+)

diff --git a/dom/bindings/ToJSValue.cpp b/dom/bindings/ToJSValue.cpp
index 42122716565f..4fea13b51692 100644
--- a/dom/bindings/ToJSValue.cpp
+++ b/dom/bindings/ToJSValue.cpp
@@ -60,5 +60,19 @@ ToJSValue(JSContext* aCx,
   return ToJSValue(aCx, exception, aValue);
 }
 
+bool
+ToJSValue(JSContext* aCx,
+          ErrorResult& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  MOZ_ASSERT(aArgument.Failed());
+  ThrowMethodFailedWithDetails(aCx, aArgument, "", "");
+  if (!JS_GetPendingException(aCx, aValue)) {
+    return false;
+  }
+  JS_ClearPendingException(aCx);
+  return true;
+}
+
 } // namespace dom
 } // namespace mozilla
diff --git a/dom/bindings/ToJSValue.h b/dom/bindings/ToJSValue.h
index c300307f59f1..49d7d35d04c6 100644
--- a/dom/bindings/ToJSValue.h
+++ b/dom/bindings/ToJSValue.h
@@ -261,6 +261,14 @@ ToJSValue(JSContext* aCx,
           nsresult aArgument,
           JS::MutableHandle<JS::Value> aValue);
 
+// Accept ErrorResult, for use in rejections, and create an exception
+// representing the failure.  Note, the ErrorResult must indicate a failure
+// with aArgument.Failure() returning true.
+bool
+ToJSValue(JSContext* aCx,
+          ErrorResult& aArgument,
+          JS::MutableHandle<JS::Value> aValue);
+
 // Accept pointers to other things we accept
 template <typename T>
 typename EnableIf<IsPointer<T>::value, bool>::Type
diff --git a/dom/promise/Promise.h b/dom/promise/Promise.h
index 8c71421ffbc7..b76433e509aa 100644
--- a/dom/promise/Promise.h
+++ b/dom/promise/Promise.h
@@ -101,6 +101,11 @@ public:
     MaybeSomething(aArg, &Promise::MaybeReject);
   }
 
+  inline void MaybeReject(ErrorResult& aArg) {
+    MOZ_ASSERT(aArg.Failed());
+    MaybeSomething(aArg, &Promise::MaybeReject);
+  }
+
   void MaybeReject(const nsRefPtr<MediaStreamError>& aArg);
 
   // DO NOT USE MaybeRejectBrokenly with in new code.  Promises should be