SkPDF: record milestone version in Producer string

tools/milestone.py

+#!/usr/bin/env python
+# Copyright 2016 Google Inc.
+#
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os
+import sys
+
+milestone_file = 'include/core/SkMilestone.h'
+
+usage = '''
+usage:
+  git fetch
+  git checkout -b change_milestone origin/master
+  python %s MILESTONE_NUMBER
+  git add %s
+  git commit -m "Update Skia milestone."
+  git cl land
+
+'''
+try:
+  milestone = int(sys.argv[1])
+  assert milestone > 0
+except (IndexError, ValueError, AssertionError):
+  sys.stderr.write(usage % (sys.argv[0], milestone_file))
+  exit(1)
+
+text = '''/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#ifndef SK_MILESTONE
+#define SK_MILESTONE %d
+#endif
+'''
+
+os.chdir(os.path.join(os.path.dirname(__file__), os.pardir))
+
+with open(milestone_file, 'w') as o:
+  o.write(text % milestone)
+
+with open(milestone_file, 'r') as f:
+  sys.stdout.write(f.read())