Check in generated Dart bindings and add presubmit script

PRESUBMIT.py

 # Copyright (c) 2012 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.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl.
 """
 
@@ skipping 1045 matching lines @@
     if f.LocalPath().endswith(('.h', '.c', '.cc', '.m', '.mm')):
       for lnum, line in f.ChangedContents():
         # Disallow Foo(*my_scoped_thing.Pass()); See crbug.com/418297.
         if input_api.re.search(r'\*[a-zA-Z0-9_]+\.Pass\(\)', line):
           errors.append(output_api.PresubmitError(
             ('%s:%d uses *foo.Pass() to delete the contents of scoped_ptr. ' +
              'See crbug.com/418297.') % (f.LocalPath(), lnum)))
   return errors
 
 
+def _CheckDartBindings(input_api, output_api):
+  """Check that generated .mojom.dart files are current"""
+  args = [input_api.python_executable,
+          'mojo/dart/tools/presubmit/check_mojom_dart.py',
+          '--affected-files']
+  files = []
+  for f in input_api.AffectedFiles():
+    files.append(f.LocalPath())
+  args.extend(files)
+  try:
+    input_api.subprocess.check_output(args)
+    return []
+  except input_api.subprocess.CalledProcessError, error:
+    return [output_api.PresubmitError(
+        'Dart bindings need to be updated.',
+        long_text=error.output)]
+
+
 def CheckChangeOnUpload(input_api, output_api):
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   results.extend(_CheckValidHostsInDEPS(input_api, output_api))
   results.extend(_CheckJavaStyle(input_api, output_api))
+  results.extend(_CheckDartBindings(input_api, output_api))
   results.extend(
       input_api.canned_checks.CheckGNFormatted(input_api, output_api))
   return results
 
 
 def GetDefaultTryConfigs(bots=None):
   """Returns a list of ('bot', set(['tests']), optionally filtered by [bots].
 
   If 'bots' is specified, will only return configurations for bots in that list.
   """
@@ skipping 47 matching lines @@
       'Mojo Linux ASan Try',
       'Mojo Linux Try',
   ]
 
   return GetDefaultTryConfigs(builders)
 
 def PostUploadHook(cl, change, output_api):
   import subprocess
   subprocess.check_call(["git", "cl", "try"])
   return []