Fixes dispatch files to return exit codes in several places

build/android/pylib/uiautomator/dispatch.py

 # Copyright (c) 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.
 
 """Dispatches the uiautomator tests."""
 
 import logging
 import os
 
 from pylib import android_commands
+from pylib import constants
 from pylib.base import base_test_result
 from pylib.base import shard
 from pylib.utils import report_results
 
 import test_package
 import test_runner
 
 
 def Dispatch(options):
   """Dispatches uiautomator tests onto connected device(s).
 
   If possible, this method will attempt to shard the tests to
   all connected devices. Otherwise, dispatch and run tests on one device.
 
   Args:
     options: Command line options.
 
   Returns:
     A tuple of (base_test_result.TestRunResults object, exit code)
 
   Raises:
     Exception: when there are no attached devices.
   """
   test_pkg = test_package.TestPackage(
       options.uiautomator_jar, options.uiautomator_info_jar)
   tests = test_pkg._GetAllMatchingTests(
       options.annotations, options.exclude_annotations, options.test_filter)
   if not tests:
-    logging.warning('No uiautomator tests to run with current args.')
-    return base_test_result.TestRunResults()
+    logging.error('No uiautomator tests to run with current args.')
+    return (base_test_result.TestRunResults(), constants.ERROR_EXIT_CODE)
 
   attached_devices = android_commands.GetAttachedDevices()
   if not attached_devices:
     raise Exception('There are no devices online.')
 
   if options.test_device:
     assert options.test_device in attached_devices
     attached_devices = [options.test_device]
 
   def TestRunnerFactory(device, shard_index):
     return test_runner.TestRunner(
         options, device, shard_index, test_pkg, [])
 
   return shard.ShardAndRunTests(TestRunnerFactory, attached_devices,
                                 tests, options.build_type,
                                 num_retries=options.num_retries)