[mojo-edk] Add support for transferring mach ports.

mojo/edk/embedder/platform_handle.h

 // 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.
 
 #ifndef MOJO_EDK_EMBEDDER_PLATFORM_HANDLE_H_
 #define MOJO_EDK_EMBEDDER_PLATFORM_HANDLE_H_
 
 #include "build/build_config.h"
 #include "mojo/edk/system/system_impl_export.h"
 
@@ skipping 12 matching lines @@
   explicit PlatformHandle(int handle) : handle(handle) {}
 #if defined(OS_MACOSX) && !defined(OS_IOS)
   explicit PlatformHandle(mach_port_t port)
       : type(Type::MACH), port(port) {}
 #endif
 
   void CloseIfNecessary();
 
   bool is_valid() const {
 #if defined(OS_MACOSX) && !defined(OS_IOS)
-    if (type == Type::MACH)
+    if (type == Type::MACH || type == Type::MACH_NAME)
       return port != MACH_PORT_NULL;
 #endif
     return handle != -1;
   }
 
   enum class Type {
     POSIX,
 #if defined(OS_MACOSX) && !defined(OS_IOS)
     MACH,
+    // MACH_NAME isn't a real Mach port. But rather the "name" of one that can
+    // be resolved to a real port later. This distinction is needed so that the
+    // "port" doesn't try to be closed if CloseIfNecessary() is called. Having
+    // this also allows us to do checks in other places.
+    MACH_NAME,
 #endif
   };
   Type type = Type::POSIX;
 
   int handle = -1;
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
   mach_port_t port = MACH_PORT_NULL;
 #endif
 };
 #elif defined(OS_WIN)
 struct MOJO_SYSTEM_IMPL_EXPORT PlatformHandle {
   PlatformHandle() : handle(INVALID_HANDLE_VALUE) {}
   explicit PlatformHandle(HANDLE handle) : handle(handle) {}
 
   void CloseIfNecessary();
 
   bool is_valid() const { return handle != INVALID_HANDLE_VALUE; }
 
   HANDLE handle;
 };
 #else
 #error "Platform not yet supported."
 #endif
 
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_EMBEDDER_PLATFORM_HANDLE_H_