Make blink_trybot recipe work on windows

scripts/slave/recipe_modules/chromium/api.py

 # Copyright 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.
 
 from slave import recipe_api
 
 class ChromiumApi(recipe_api.RecipeApi):
   def get_config_defaults(self, _config_name):
     return {
       'HOST_PLATFORM': self.m.platform.name,
@@ skipping 16 matching lines @@
     if self.c.compile_py.compiler:
       args += ['--compiler', self.c.compile_py.compiler]
     args.append('--')
     args.extend(targets)
     return self.m.step('compile', args)
 
   def runtests(self, test, args=None, xvfb=False, name=None, **kwargs):
     """Return a runtest.py invocation."""
     args = args or []
     assert isinstance(args, list)
-    test_args = [test] + args
 
     python_arg = []
     t_name, ext = self.m.path.splitext(self.m.path.basename(test))
     if ext == '.py':
       python_arg = ['--run-python-script']
+    elif self.m.platform.is_win and ext == '':
+      test += '.exe'
+
+    test_args = [test] + args
 
     return self.m.step(name or t_name, [
       'python', self.m.path.build('scripts', 'slave', 'runtest.py'),
       '--target', self.c.BUILD_CONFIG,
       '--build-dir', self.m.path.checkout(self.c.build_dir),
       ('--xvfb' if xvfb else '--no-xvfb')]
       + self.m.json.property_args()
       + python_arg
       + test_args,
       **kwargs
     )
 
   def runhooks(self):
     """Run the build-configuration hooks for chromium."""
     return self.m.step(
       'gclient runhooks',
       [self.m.path.depot_tools('gclient', wrapper=True), 'runhooks'],
       env=self.c.gyp_env.as_jsonish(),
     )