Initialize IPC:ChannelHandle from existing HANDLE

ipc/ipc_channel_handle.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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.
 
 #ifndef IPC_IPC_CHANNEL_HANDLE_H_
 #define IPC_IPC_CHANNEL_HANDLE_H_
 #pragma once
 
 #include <string>
 
 #include "build/build_config.h"
 
 #if defined(OS_POSIX)
 #include "base/file_descriptor_posix.h"
 #endif
+#if defined(OS_WIN)

[jam, 2012/01/20 23:25:06]

nit: in this file and ipc_message_utils.cc, if there's a OS_POSIX/OS_WIN follow
each other, it's slightly more readable to use #elif

+#include <windows.h>
+#endif  // defined (OS_WIN)
 
 // On Windows, any process can create an IPC channel and others can fetch
 // it by name.  We pass around the channel names over IPC.
+// On Windows the initialization of ChannelHandle with an existing pipe
+// handle is provided for convenience.
+// NOTE: A ChannelHandle with a pipe handle Will NOT be marshalled over IPC.
+
 // On POSIX, we instead pass around handles to channel endpoints via IPC.
 // When it's time to IPC a new channel endpoint around, we send both the
 // channel name as well as a base::FileDescriptor, which is itself a special
 // type that knows how to copy a socket endpoint over IPC.
 //
-// In sum, when passing a handle to a channel over IPC, use this data structure
-// to work on both Windows and POSIX.
+// In sum, this data structure can be used to pass channel information by name
+// in both Windows and Posix. When passing a handle to a channel over IPC,
+// use this data structure only for POSIX.
 
 namespace IPC {
 
 struct ChannelHandle {
   // Note that serialization for this object is defined in the ParamTraits
   // template specialization in ipc_message_utils.h.
   ChannelHandle() {}
   // The name that is passed in should be an absolute path for Posix.
   // Otherwise there may be a problem in IPC communication between
   // processes with different working directories.
   ChannelHandle(const std::string& n) : name(n) {}
   ChannelHandle(const char* n) : name(n) {}
+#if defined(OS_WIN)
+  explicit ChannelHandle(HANDLE h) : pipe(h) {}
+#endif  // defined (OS_WIN)
 #if defined(OS_POSIX)
   ChannelHandle(const std::string& n, const base::FileDescriptor& s)
       : name(n), socket(s) {}
 #endif  // defined(OS_POSIX)
 
   std::string name;
 #if defined(OS_POSIX)
   base::FileDescriptor socket;
 #endif  // defined(OS_POSIX)
-
+#if defined(OS_WIN)
+  // A simple container to automatically initialize pipe handle
+  struct PipeHandle {
+    PipeHandle() : handle(NULL) {}
+    PipeHandle(HANDLE h) : handle(h) {}
+    HANDLE handle;
+  };
+  PipeHandle pipe;
+#endif  // defined (OS_WIN)
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_CHANNEL_HANDLE_H_