Revert of [mojo-edk] Serialise windows handles into an "extra header" section.

mojo/edk/system/channel_posix.cc

 // Copyright 2016 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 "mojo/edk/system/channel.h"
 
 #include <errno.h>
 #include <sys/uio.h>
 
 #include <algorithm>
@@ skipping 116 matching lines @@
     if (write_error) {
       // Do not synchronously invoke OnError(). Write() may have been called by
       // the delegate and we don't want to re-enter it.
       io_task_runner_->PostTask(FROM_HERE,
                                 base::Bind(&ChannelPosix::OnError, this));
     }
   }
 
   ScopedPlatformHandleVectorPtr GetReadPlatformHandles(
       size_t num_handles,
-      const void* extra_header,
-      size_t extra_header_size) override {
+      void** payload,
+      size_t* payload_size) override {
     if (incoming_platform_handles_.size() < num_handles)
       return nullptr;
-
     ScopedPlatformHandleVectorPtr handles(
         new PlatformHandleVector(num_handles));
     for (size_t i = 0; i < num_handles; ++i) {
       (*handles)[i] = incoming_platform_handles_.front();
       incoming_platform_handles_.pop_front();
     }
-
     return handles;
   }
 
  private:
   ~ChannelPosix() override {
     DCHECK(!read_watcher_);
     DCHECK(!write_watcher_);
     for (auto handle : incoming_platform_handles_)
       handle.CloseIfNecessary();
   }
@@ skipping 291 matching lines @@
 // static
 scoped_refptr<Channel> Channel::Create(
     Delegate* delegate,
     ScopedPlatformHandle platform_handle,
     scoped_refptr<base::TaskRunner> io_task_runner) {
   return new ChannelPosix(delegate, std::move(platform_handle), io_task_runner);
 }
 
 }  // namespace edk
 }  // namespace mojo