WIP: A couple of more ChannelMojo speedup ideas

third_party/mojo/src/mojo/edk/system/dispatcher.cc

Index: third_party/mojo/src/mojo/edk/system/dispatcher.cc
diff --git a/third_party/mojo/src/mojo/edk/system/dispatcher.cc b/third_party/mojo/src/mojo/edk/system/dispatcher.cc
index e2f2b8784f4684c9d1c074e1a7aae65e8c6ccd66..dda757017acf0247fd470a169f1568436536b234 100644
--- a/third_party/mojo/src/mojo/edk/system/dispatcher.cc
+++ b/third_party/mojo/src/mojo/edk/system/dispatcher.cc
@@ -246,6 +246,12 @@ void Dispatcher::RemoveAwakable(Awakable* awakable,
   RemoveAwakableImplNoLock(awakable, handle_signals_state);
 }
 
+MojoResult Dispatcher::SetAsyncMessageCallback(
+    const AsyncMessageCallback& callback) {
+  base::AutoLock locker(lock_);
+  return SetAsyncMessageCallbackImplNoLock(callback);
+}
+
 Dispatcher::Dispatcher() : is_closed_(false) {
 }
 
@@ -395,6 +401,13 @@ void Dispatcher::RemoveAwakableImplNoLock(Awakable* /*awakable*/,
     *signals_state = HandleSignalsState();
 }
 
+MojoResult Dispatcher::SetAsyncMessageCallbackImplNoLock(
+    const AsyncMessageCallback& callback) {
+  lock_.AssertAcquired();
+  NOTREACHED();
+  return MOJO_RESULT_INTERNAL;
+}
+
 void Dispatcher::StartSerializeImplNoLock(Channel* /*channel*/,
                                           size_t* max_size,
                                           size_t* max_platform_handles) {