Remove IPC::Endpoint.

ipc/ipc_message.h

Index: ipc/ipc_message.h
diff --git a/ipc/ipc_message.h b/ipc/ipc_message.h
index b8689639f262fb4a9fa38803a87511f3cf7a69c5..6bf18dec4254548003c3dbbeab4720165bacca64 100644
--- a/ipc/ipc_message.h
+++ b/ipc/ipc_message.h
@@ -213,9 +213,6 @@ class IPC_EXPORT Message : public base::Pickle {
   // Whether the message has any brokerable attachments.
   bool HasBrokerableAttachments() const;
 
-  void set_sender_pid(base::ProcessId id) { sender_pid_ = id; }
-  base::ProcessId get_sender_pid() const { return sender_pid_; }
-
 #ifdef IPC_MESSAGE_LOG_ENABLED
   // Adds the outgoing time from Time::Now() at the end of the message and sets
   // a bit to indicate that it's been added.
@@ -284,10 +281,6 @@ class IPC_EXPORT Message : public base::Pickle {
     return attachment_set_.get();
   }
 
-  // The process id of the sender of the message. This member is populated with
-  // a valid value for every message dispatched to listeners.
-  base::ProcessId sender_pid_;
-
 #ifdef IPC_MESSAGE_LOG_ENABLED
   // Used for logging.
   mutable int64_t received_time_;