Add a GUID to base::SharedMemoryHandle.

mojo/public/cpp/system/platform_handle.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/public/cpp/system/platform_handle.h"
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
 #include <mach/mach.h>
 #include "base/mac/mach_logging.h"
 #endif
@@ skipping 96 matching lines @@
       handle.release().value(), &platform_handle, &num_bytes, &flags);
   if (result != MOJO_RESULT_OK)
     return result;
 
   if (size)
     *size = num_bytes;
 
   if (read_only)
     *read_only = flags & MOJO_PLATFORM_SHARED_BUFFER_HANDLE_FLAG_READ_ONLY;
 
+  // TODO(rockot): Pass GUIDs through Mojo. https://crbug.com/713763.
+  base::UnguessableToken guid = base::UnguessableToken::Create();
 #if defined(OS_MACOSX) && !defined(OS_IOS)
   CHECK_EQ(platform_handle.type, MOJO_PLATFORM_HANDLE_TYPE_MACH_PORT);
   *memory_handle = base::SharedMemoryHandle(
-      static_cast<mach_port_t>(platform_handle.value), num_bytes);
+      static_cast<mach_port_t>(platform_handle.value), num_bytes, guid);
 #elif defined(OS_POSIX)
   CHECK_EQ(platform_handle.type, MOJO_PLATFORM_HANDLE_TYPE_FILE_DESCRIPTOR);
   *memory_handle = base::SharedMemoryHandle(
-      base::FileDescriptor(static_cast<int>(platform_handle.value), false));
+      base::FileDescriptor(static_cast<int>(platform_handle.value), false),
+      guid);
 #elif defined(OS_WIN)
   CHECK_EQ(platform_handle.type, MOJO_PLATFORM_HANDLE_TYPE_WINDOWS_HANDLE);
-  *memory_handle =
-      base::SharedMemoryHandle(reinterpret_cast<HANDLE>(platform_handle.value));
+  *memory_handle = base::SharedMemoryHandle(
+      reinterpret_cast<HANDLE>(platform_handle.value), guid);
 #endif
 
   return MOJO_RESULT_OK;
 }
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
 ScopedHandle WrapMachPort(mach_port_t port) {
   kern_return_t kr =
       mach_port_mod_refs(mach_task_self(), port, MACH_PORT_RIGHT_SEND, 1);
   MACH_LOG_IF(ERROR, kr != KERN_SUCCESS, kr)
@@ skipping 21 matching lines @@
   if (result != MOJO_RESULT_OK)
     return result;
 
   CHECK_EQ(platform_handle.type, MOJO_PLATFORM_HANDLE_TYPE_MACH_PORT);
   *port = static_cast<mach_port_t>(platform_handle.value);
   return MOJO_RESULT_OK;
 }
 #endif  // defined(OS_MACOSX) && !defined(OS_IOS)
 
 }  // namespace mojo