ipc: Create an unforgeable mechanism to get the process id of the sender.

ipc/ipc_channel_posix.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ipc/ipc_channel_posix.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <stddef.h>
 #include <sys/socket.h>
@@ skipping 933 matching lines @@
           NOTREACHED();
         }
       } else {
         QueueCloseFDMessage(fd, hops);
       }
       break;
 #endif
   }
 }
 
+base::ProcessId ChannelPosix::GetSenderPID() {
+  return GetPeerPID();
+}
+
 void ChannelPosix::Close() {
   // Close can be called multiple time, so we need to make sure we're
   // idempotent.
 
   ResetToAcceptingConnectionState();
 
   if (must_unlink_) {
     unlink(pipe_name_.c_str());
     must_unlink_ = false;
   }
@@ skipping 69 matching lines @@
 }
 
 #if defined(OS_LINUX)
 // static
 void Channel::SetGlobalPid(int pid) {
   ChannelPosix::SetGlobalPid(pid);
 }
 #endif  // OS_LINUX
 
 }  // namespace IPC