Android test_runner.py: Eliminate unused "adb devices" call for gtests

build/android/test_runner.py

 #!/usr/bin/env python
 #
 # 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.
 
 """Runs all types of tests from one unified interface."""
 
 import argparse
 import collections
@@ skipping 895 matching lines @@
     Integer indicated exit code.
 
   Raises:
     Exception: Unknown command name passed in, or an exception from an
         individual test runner.
   """
   command = args.command
 
   ProcessCommonOptions(args)
 
   if args.enable_platform_mode:

[jbudorick, 2015/10/09 00:28:48]

alternatively, we could just switch this to

  if args.enable_platform_mode or command == 'gtest':

(this is where I'm going with https://codereview.chromium.org/1387933005/, but
that CL will take a little while)

[agrieve, 2015/10/09 00:58:54]

Interesting! Sounds good except with the change as-is it also skips the device
check for 'python' and 'junit'. Update description to mention this.

     return RunTestsInPlatformMode(args, parser)
 
-  if command in constants.LOCAL_MACHINE_TESTS:
-    devices = []
-  else:
-    devices = _GetAttachedDevices(args.blacklist_file, args.test_device)
-
   forwarder.Forwarder.RemoveHostLog()
   if not ports.ResetTestServerPortAllocation():
     raise Exception('Failed to reset test server port.')
 
+  def get_devices():
+    if command in constants.LOCAL_MACHINE_TESTS:
+      return []
+    return _GetAttachedDevices(args.blacklist_file, args.test_device)
+
   if command == 'gtest':
     return RunTestsInPlatformMode(args, parser)
   elif command == 'linker':
-    return _RunLinkerTests(args, devices)
+    return _RunLinkerTests(args, get_devices())
   elif command == 'instrumentation':
-    return _RunInstrumentationTests(args, devices)
+    return _RunInstrumentationTests(args, get_devices())
   elif command == 'uiautomator':
-    return _RunUIAutomatorTests(args, devices)
+    return _RunUIAutomatorTests(args, get_devices())
   elif command == 'junit':
     return _RunJUnitTests(args)
   elif command == 'monkey':
-    return _RunMonkeyTests(args, devices)
+    return _RunMonkeyTests(args, get_devices())
   elif command == 'perf':
-    return _RunPerfTests(args, devices)
+    return _RunPerfTests(args, get_devices())
   elif command == 'python':
     return _RunPythonTests(args)
   else:
     raise Exception('Unknown test type.')
 
 
 _SUPPORTED_IN_PLATFORM_MODE = [
   # TODO(jbudorick): Add support for more test types.
   'gtest',
   'instrumentation',
@@ skipping 98 matching lines @@
     if e.is_infra_error:
       return constants.INFRA_EXIT_CODE
     return constants.ERROR_EXIT_CODE
   except: # pylint: disable=W0702
     logging.exception('Unrecognized error occurred.')
     return constants.ERROR_EXIT_CODE
 
 
 if __name__ == '__main__':
   sys.exit(main())