ipc: Add the inner class OutputElement to Channel.

ipc/ipc_channel.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.h"
 
 #include <stdint.h>
 
 #include <limits>
 
@@ skipping 25 matching lines @@
   int process_id = -1;
 #else
   int process_id = base::GetCurrentProcId();
 #endif
   return base::StringPrintf("%d.%u.%d",
       process_id,
       g_last_id.GetNext(),
       base::RandInt(0, std::numeric_limits<int32_t>::max()));
 }
 
+Channel::OutputElement::OutputElement(Message* message)
+    : message_(message), buffer_(nullptr), length_(0) {}
+
+Channel::OutputElement::OutputElement(void* buffer, size_t length)
+    : message_(nullptr), buffer_(buffer), length_(length) {}
+
+Channel::OutputElement::~OutputElement() {
+  free(buffer_);
+}
+
 }  // namespace IPC