Run dartfmt when invoking git cl format.

dart_format.py

Index: dart_format.py
diff --git a/dart_format.py b/dart_format.py
new file mode 100755
index 0000000000000000000000000000000000000000..ee07efe2e3c8141dea679b1fbaa1ed0d9c9e530c
--- /dev/null
+++ b/dart_format.py
@@ -0,0 +1,58 @@
+#!/usr/bin/python
+# 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.
+
+"""Redirects to the version of dartfmt checked into a gclient repo.
+
+dartfmt binaries are pulled down during gclient sync in the mojo repo.
+
+This tool is named dart_format.py instead of dartfmt to parallel
+clang_format.py, which is in this same repository."""
+
+import os
+import subprocess
+import sys
+
+import gclient_utils
+
+class NotFoundError(Exception):
+  """A file could not be found."""
+  def __init__(self, e):
+    Exception.__init__(self,
+        'Problem while looking for dartfmt in Chromium source tree:\n'
+        '  %s' % e)
+
+
+def FindDartFmtToolInChromiumTree():
+  """Return a path to the dartfmt executable, or die trying."""
+  primary_solution_path = gclient_utils.GetPrimarySolutionPath()
+  if not primary_solution_path:
+    raise NotFoundError(
+        'Could not find checkout in any parent of the current path.')
+
+  dartfmt_path = os.path.join(primary_solution_path, 'third_party', 'dart-sdk',
+                              'dart-sdk', 'bin', 'dartfmt')
+  if not os.path.exists(dartfmt_path):
+    raise NotFoundError('File does not exist: %s' % dartfmt_path)
+  return dartfmt_path
+
+
+def main(args):
+  try:
+    tool = FindDartFmtToolInChromiumTree()
+  except NotFoundError, e:
+    print >> sys.stderr, e
+    sys.exit(1)
+
+  # Add some visibility to --help showing where the tool lives, since this
+  # redirection can be a little opaque.
+  help_syntax = ('-h', '--help', '-help', '-help-list', '--help-list')
+  if any(match in args for match in help_syntax):
+    print '\nDepot tools redirects you to the dartfmt at:\n    %s\n' % tool
+
+  return subprocess.call([tool] + sys.argv[1:])
+
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv))