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 <limits>
 
 #include "base/atomic_sequence_num.h"
 #include "base/rand_util.h"
@@ skipping 23 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>::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_);
+}
+
+size_t Channel::OutputElement::size() const {
+  if (message_)

[Tom Sepez, 2015/09/10 15:41:05]

nit: I'd use the ? operator here and below, just because it all fits on one
line.  Also, do you want these in the header to aid in inlining?

[erikchen, 2015/09/10 18:43:59]

I switched to the ternary operator, and moved the code into the header.

+    return message_->size();
+  return length_;
+}
+
+const void* Channel::OutputElement::data() const {
+  if (message_)

[Tom Sepez, 2015/09/10 15:41:05]

do you want to assert that there isn't both message and buffer_?

[erikchen, 2015/09/10 18:43:59]

Given that that assertion is enforced by the constructor, the only way for both
message and buffer_ to exist is memory corruption, which is not something I'm
inclined to add assertions for.

+    return message_->data();
+  return buffer_;
+}
+
 }  // namespace IPC