Adds some code to help isolate where crash is happening

mojo/message_pump/message_pump_mojo_unittest.cc

Index: mojo/message_pump/message_pump_mojo_unittest.cc
diff --git a/mojo/message_pump/message_pump_mojo_unittest.cc b/mojo/message_pump/message_pump_mojo_unittest.cc
index 51f3670c513d94730309de832cb1feb0e9a4f88b..eea8e2333dbb3f2bceb20b6ea34496b8e83a3e16 100644
--- a/mojo/message_pump/message_pump_mojo_unittest.cc
+++ b/mojo/message_pump/message_pump_mojo_unittest.cc
@@ -60,8 +60,7 @@ TEST(MessagePumpMojo, RunUntilIdle) {
   base::MessageLoop message_loop(MessagePumpMojo::Create());
   CountingMojoHandler handler;
   MessagePipe handles;
-  MessagePumpMojo::current()->AddHandler(&handler,
-                                         handles.handle0.get(),
+  MessagePumpMojo::current()->AddHandler(0, &handler, handles.handle0.get(),
                                          MOJO_HANDLE_SIGNAL_READABLE,
                                          base::TimeTicks());
   WriteMessageRaw(
@@ -81,8 +80,7 @@ TEST(MessagePumpMojo, Observer) {
 
   CountingMojoHandler handler;
   MessagePipe handles;
-  MessagePumpMojo::current()->AddHandler(&handler,
-                                         handles.handle0.get(),
+  MessagePumpMojo::current()->AddHandler(0, &handler, handles.handle0.get(),
                                          MOJO_HANDLE_SIGNAL_READABLE,
                                          base::TimeTicks());
   WriteMessageRaw(
@@ -108,9 +106,7 @@ TEST(MessagePumpMojo, UnregisterAfterDeadline) {
   CountingMojoHandler handler;
   MessagePipe handles;
   MessagePumpMojo::current()->AddHandler(
-      &handler,
-      handles.handle0.get(),
-      MOJO_HANDLE_SIGNAL_READABLE,
+      0, &handler, handles.handle0.get(), MOJO_HANDLE_SIGNAL_READABLE,
       base::TimeTicks::Now() - base::TimeDelta::FromSeconds(1));
   for (int i = 0; i < 2; ++i) {
     base::RunLoop run_loop;