diff -r 000000000000 -r 6474c204b198 ipc/ipdl/test/cxx/TestRaceDeferral.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ipc/ipdl/test/cxx/TestRaceDeferral.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,117 @@
+#include "TestRaceDeferral.h"
+
+#include "IPDLUnitTests.h"      // fail etc.
+
+using namespace mozilla::ipc;
+typedef mozilla::ipc::MessageChannel::Message Message;
+
+namespace mozilla {
+namespace _ipdltest {
+
+static RacyInterruptPolicy
+MediateRace(const Message& parent, const Message& child)
+{
+    return (PTestRaceDeferral::Msg_Win__ID == parent.type()) ?
+        RIPParentWins : RIPChildWins;
+}
+
+//-----------------------------------------------------------------------------
+// parent
+
+TestRaceDeferralParent::TestRaceDeferralParent()
+    : mProcessedLose(false)
+{
+    MOZ_COUNT_CTOR(TestRaceDeferralParent);
+}
+
+TestRaceDeferralParent::~TestRaceDeferralParent()
+{
+    MOZ_COUNT_DTOR(TestRaceDeferralParent);
+
+    if (!mProcessedLose)
+        fail("never processed Lose");
+}
+
+void
+TestRaceDeferralParent::Main()
+{
+    Test1();
+
+    Close();
+}
+
+void
+TestRaceDeferralParent::Test1()
+{
+    if (!SendStartRace())
+        fail("sending StartRace");
+
+    if (!CallWin())
+        fail("calling Win");
+    if (mProcessedLose)
+        fail("Lose didn't lose");
+
+    if (!CallRpc())
+        fail("calling Rpc");
+    if (!mProcessedLose)
+        fail("didn't resolve Rpc vs. Lose 'race' correctly");
+}
+
+bool
+TestRaceDeferralParent::AnswerLose()
+{
+    if (mProcessedLose)
+        fail("processed Lose twice");
+    mProcessedLose = true;
+    return true;
+}
+
+RacyInterruptPolicy
+TestRaceDeferralParent::MediateInterruptRace(const Message& parent,
+                                       const Message& child)
+{
+    return MediateRace(parent, child);
+}
+
+//-----------------------------------------------------------------------------
+// child
+
+TestRaceDeferralChild::TestRaceDeferralChild()
+{
+    MOZ_COUNT_CTOR(TestRaceDeferralChild);
+}
+
+TestRaceDeferralChild::~TestRaceDeferralChild()
+{
+    MOZ_COUNT_DTOR(TestRaceDeferralChild);
+}
+
+bool
+TestRaceDeferralChild::RecvStartRace()
+{
+    if (!CallLose())
+        fail("calling Lose");
+    return true;
+}
+
+bool
+TestRaceDeferralChild::AnswerWin()
+{
+    return true;
+}
+
+bool
+TestRaceDeferralChild::AnswerRpc()
+{
+    return true;
+}
+
+RacyInterruptPolicy
+TestRaceDeferralChild::MediateInterruptRace(const Message& parent,
+                                      const Message& child)
+{
+    return MediateRace(parent, child);
+}
+
+} // namespace _ipdltest
+} // namespace mozilla