Mojo: Dispatcher::MessageInTransitAccess functions don't need to take the lock.

mojo/system/message_pipe_dispatcher.cc

Index: mojo/system/message_pipe_dispatcher.cc
diff --git a/mojo/system/message_pipe_dispatcher.cc b/mojo/system/message_pipe_dispatcher.cc
index bf9e5b036f486733a7ab1cb14b5acd7e7022b295..a22b3a716dac3539d124b70073e1dd7b19efec88 100644
--- a/mojo/system/message_pipe_dispatcher.cc
+++ b/mojo/system/message_pipe_dispatcher.cc
@@ -174,14 +174,14 @@ void MessagePipeDispatcher::RemoveWaiterImplNoLock(Waiter* waiter) {
 
 size_t MessagePipeDispatcher::GetMaximumSerializedSizeImplNoLock(
     const Channel* /*channel*/) const {
-  lock().AssertAcquired();
+  DCHECK(HasOneRef());  // Only one ref => no need to take the lock.
   return sizeof(SerializedMessagePipeDispatcher);
 }
 
 bool MessagePipeDispatcher::SerializeAndCloseImplNoLock(Channel* channel,
                                                         void* destination,
                                                         size_t* actual_size) {
-  lock().AssertAcquired();
+  DCHECK(HasOneRef());  // Only one ref => no need to take the lock.
 
   // Convert the local endpoint to a proxy endpoint (moving the message queue).
   message_pipe_->ConvertLocalToProxy(port_);