handler/mac: Log a warning when an exception message has a suspicious

util/mach/exception_ports_test.cc

Index: util/mach/exception_ports_test.cc
diff --git a/util/mach/exception_ports_test.cc b/util/mach/exception_ports_test.cc
index 8948eae791668123ced9510c5a824d1f09d91a26..155e9187fa22cda9090ca98cdf70c013febef857 100644
--- a/util/mach/exception_ports_test.cc
+++ b/util/mach/exception_ports_test.cc
@@ -197,6 +197,8 @@ class TestExceptionPorts : public MachMultiprocess,
       SetExpectedChildTermination(kTerminationSignal, signal);
     }
 
+    EXPECT_EQ(0, AuditPIDFromMachMessageTrailer(trailer));
+
     return ExcServerSuccessfulReturnValue(behavior, false);
   }
 
@@ -443,7 +445,7 @@ class TestExceptionPorts : public MachMultiprocess,
       kern_return_t kr =
           MachMessageServer::Run(&universal_mach_exc_server,
                                  local_port,
-                                 MACH_MSG_OPTION_NONE,
+                                 kMachMessageReceiveAuditTrailer,
                                  MachMessageServer::kOneShot,
                                  MachMessageServer::kReceiveLargeError,
                                  kTimeoutMs);