Set window size when running dev_server tests to reduce the chance of flake

catapult_build/run_dev_server_tests.py

 #!/usr/bin/env 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.
 
 import argparse
 import logging
 import os
 import re
 import shutil
@@ skipping 231 matching lines @@
           path = os.path.join(tmpdir, path)
           os.chmod(path, os.stat(path).st_mode | stat.S_IEXEC)
       chrome_info = version
     chrome_command = [
         chrome_path,
         '--user-data-dir=%s' % user_data_dir,
         '--no-sandbox',
         '--no-experiments',
         '--no-first-run',
         '--noerrdialogs',
+        '--window-size=1280,1024',
         ('http://localhost:%s/%s/tests.html?' % (port, args.tests)) +
             'headless=true&testTypeToRun=all',
     ]
     print "Starting Chrome %s..." % chrome_info
     chrome_process = subprocess.Popen(
         chrome_command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
     print "Waiting for tests to finish..."
     server_out, server_err = server_process.communicate()
     print "Killing Chrome..."
     if sys.platform == 'win32':
@@ skipping 19 matching lines @@
       try:
         shutil.rmtree(tmpdir)
         shutil.rmtree(user_data_dir)
       except OSError as e:
         logging.error('Error cleaning up temp dirs %s and %s: %s' % (
             tmpdir, user_data_dir, e))
     if xvfb_process:
       xvfb_process.kill()
 
   sys.exit(server_process.returncode)