Mojo: (POSIX) Pass channel handle to child.

mojo/system/platform_channel.cc

 // Copyright 2013 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/system/platform_channel.h"
 
 #include "base/logging.h"
 
 namespace mojo {
 namespace system {
 
 PlatformChannel::~PlatformChannel() {
-  // Implementations must close the handle if necessary (e.g., if no one else
-  // has taken ownership).
-  DCHECK(!is_valid());
+  handle_.CloseIfNecessary();
 }
 
 PlatformChannelHandle PlatformChannel::PassHandle() {
   DCHECK(is_valid());
   PlatformChannelHandle rv = handle_;
   handle_ = PlatformChannelHandle();
   return rv;
 }
 
 PlatformChannel::PlatformChannel() {
 }
 
 PlatformServerChannel::PlatformServerChannel(const std::string& name)
     : name_(name) {
   DCHECK(!name_.empty());
 }
 
 // Static factory method.
 // static
 scoped_ptr<PlatformClientChannel> PlatformClientChannel::CreateFromHandle(
       const PlatformChannelHandle& handle) {
+  DCHECK(handle.is_valid());
   scoped_ptr<PlatformClientChannel> rv(new PlatformClientChannel());
   *rv->mutable_handle() = handle;
   return rv.Pass();
 }
 
 }  // namespace system
 }  // namespace mojo