Move description of win/setup_toolchain.py before import.

build/toolchain/win/setup_toolchain.py

Index: build/toolchain/win/setup_toolchain.py
diff --git a/build/toolchain/win/setup_toolchain.py b/build/toolchain/win/setup_toolchain.py
index 9bf7f07b2169593b11a7f3c1bfb25098ff5d550c..cc89638e19e83657f168d4b9303e5a295519edc2 100644
--- a/build/toolchain/win/setup_toolchain.py
+++ b/build/toolchain/win/setup_toolchain.py
@@ -1,13 +1,7 @@
 # Copyright (c) 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.
-
-import errno
-import os
-import re
-import subprocess
-import sys
-
+#
 # Copies the given "win tool" (which the toolchain uses to wrap compiler
 # invocations) and the environment blocks for the 32-bit and 64-bit builds on
 # Windows to the build directory.
@@ -16,6 +10,12 @@ import sys
 # win tool. The script assumes that the root build directory is the current dir
 # and the files will be written to the current directory.
 
+import errno
+import os
+import re
+import subprocess
+import sys
+
 
 def _ExtractImportantEnvironment(output_of_set):
   """Extracts environment variables required for the toolchain to run from