Mojo: (POSIX) Pass channel handle to child.

mojo/system/platform_channel_handle.h

Index: mojo/system/platform_channel_handle.h
diff --git a/mojo/system/platform_channel_handle.h b/mojo/system/platform_channel_handle.h
index abae838f12fcb4158c70d378fe62a0e0a5e1fcfd..3bb541b32c0e5091b9d6a1746fd519bce199b612 100644
--- a/mojo/system/platform_channel_handle.h
+++ b/mojo/system/platform_channel_handle.h
@@ -19,6 +19,8 @@ struct PlatformChannelHandle {
   PlatformChannelHandle() : fd(-1) {}
   explicit PlatformChannelHandle(int fd) : fd(fd) {}
 
+  void CloseIfNecessary();
+
   bool is_valid() const { return fd != -1; }
 
   int fd;
@@ -28,6 +30,8 @@ struct PlatformChannelHandle {
   PlatformChannelHandle() : handle(INVALID_HANDLE_VALUE) {}
   explicit PlatformChannelHandle(HANDLE handle) : handle(handle) {}
 
+  void CloseIfNecessary();
+
   bool is_valid() const { return handle != INVALID_HANDLE_VALUE; }
 
   HANDLE handle;