Update from https://crrev.com/327068

base/trace_event/etw_manifest/BUILD/message_compiler.py

Index: base/trace_event/etw_manifest/BUILD/message_compiler.py
diff --git a/base/trace_event/etw_manifest/BUILD/message_compiler.py b/base/trace_event/etw_manifest/BUILD/message_compiler.py
new file mode 100644
index 0000000000000000000000000000000000000000..be5927d9bec990c360861e10504553306e7ac9aa
--- /dev/null
+++ b/base/trace_event/etw_manifest/BUILD/message_compiler.py
@@ -0,0 +1,16 @@
+# 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
+# GN 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)