Remove unused IPC::Message priority.

ipc/ipc_sync_message.cc

Index: ipc/ipc_sync_message.cc
diff --git a/ipc/ipc_sync_message.cc b/ipc/ipc_sync_message.cc
index 9e3acf8e1fae1dba5a46469dae1e77b2513cd19b..52268788fb44c96f5b986b9ee60c62e4b79f8159 100644
--- a/ipc/ipc_sync_message.cc
+++ b/ipc/ipc_sync_message.cc
@@ -39,9 +39,8 @@ namespace IPC {
 SyncMessage::SyncMessage(
     int32 routing_id,
     uint32 type,
-    PriorityValue priority,
     MessageReplyDeserializer* deserializer)
-    : Message(routing_id, type, priority),
+    : Message(routing_id, type),
       deserializer_(deserializer),
       pump_messages_event_(NULL)
       {
@@ -96,8 +95,7 @@ int SyncMessage::GetMessageId(const Message& msg) {
 Message* SyncMessage::GenerateReply(const Message* msg) {
   DCHECK(msg->is_sync());
 
-  Message* reply = new Message(msg->routing_id(), IPC_REPLY_ID,
-                               msg->priority());
+  Message* reply = new Message(msg->routing_id(), IPC_REPLY_ID);
   reply->set_reply();
 
   SyncHeader header;