[mojo-edk] Initialise padding in mojo::edk::BrokerMessageHeader.

mojo/edk/system/broker_messages.h

Index: mojo/edk/system/broker_messages.h
diff --git a/mojo/edk/system/broker_messages.h b/mojo/edk/system/broker_messages.h
index 6ae92bb83fd9884e03d95d54360a196776d9a00a..a67be15d8a10ea5aa105821807acdee3ea8479be 100644
--- a/mojo/edk/system/broker_messages.h
+++ b/mojo/edk/system/broker_messages.h
@@ -41,6 +41,7 @@ inline Channel::MessagePtr CreateBrokerMessage(BrokerMessageType type,
   BrokerMessageHeader* header =
       reinterpret_cast<BrokerMessageHeader*>(message->mutable_payload());
   header->type = type;
+  header->padding = 0;
   *out_message_data = reinterpret_cast<T*>(header + 1);
   return message;
 }
@@ -54,6 +55,7 @@ inline Channel::MessagePtr CreateBrokerMessage(
   BrokerMessageHeader* header =
       reinterpret_cast<BrokerMessageHeader*>(message->mutable_payload());
   header->type = type;
+  header->padding = 0;
   return message;
 }