Share logic for generating compile DB with run_tool.py

tools/clang/scripts/generate_compdb.py

Index: tools/clang/scripts/generate_compdb.py
diff --git a/tools/clang/scripts/generate_compdb.py b/tools/clang/scripts/generate_compdb.py
new file mode 100755
index 0000000000000000000000000000000000000000..318f968729243e9e5fea52414aea8a5e602c2883
--- /dev/null
+++ b/tools/clang/scripts/generate_compdb.py
@@ -0,0 +1,38 @@
+#!/usr/bin/env python
+# Copyright 2014 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.
+
+"""
+Clang tools on Windows are still a bit busted. The tooling can't handle
+backslashes in paths, doesn't understand how to read .rsp files, etc. In
+addition, ninja generates compile commands prefixed with the ninja msvc helper,

[Nico, 2017/04/06 13:30:52]

Only if you don't use is_clang these days. In clang builds, the msvc helper
isn't' used for compiles anymore.

[dcheng, 2017/04/06 18:54:46]

Oops, forgot to update this comment. Done.

+which also confuses clang. This script generates a compile DB that should mostly
+work until clang tooling can be improved upstream.
+"""
+
+import argparse
+import os
+import sys
+
+script_dir = os.path.dirname(os.path.realpath(__file__))
+tool_dir = os.path.abspath(os.path.join(script_dir, '../pylib'))
+sys.path.insert(0, tool_dir)
+
+from clang import compile_db
+
+
+def main(argv):
+  parser = argparse.ArgumentParser()
+  parser.add_argument(
+      'build_path',
+      nargs='?',
+      help='Path to build directory',
+      default='out/Debug')
+  args = parser.parse_args()
+
+  compile_db.GenerateWithNinja(args.build_path)
+
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv[1:]))