Unify mc.exe calling in GN, set environment.

remoting/tools/build/message_compiler.py

Index: remoting/tools/build/message_compiler.py
diff --git a/remoting/tools/build/message_compiler.py b/remoting/tools/build/message_compiler.py
deleted file mode 100644
index 60b0eaa543b9d0802592335498ce1c0db74f32be..0000000000000000000000000000000000000000
--- a/remoting/tools/build/message_compiler.py
+++ /dev/null
@@ -1,16 +0,0 @@
-# Copyright 2015 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.
-
-# Runs the Microsoft Message Compiler (mc.exe). This Python adapter is for the
-# GYP build, which can only run Python and not native binaries.
-
-import subprocess
-import sys
-
-# mc writes to stderr, so this explicily redirects to stdout and eats it.
-try:
-  subprocess.check_output(["mc.exe"] + sys.argv[1:], stderr=subprocess.STDOUT)
-except subprocess.CalledProcessError as e:
-  print e.output
-  sys.exit(e.returncode)