tools/profile_chrome.py -d to select one of multiple connected android devices.

tools/profile_chrome/main.py

 #!/usr/bin/env python
 #
 # Copyright 2014 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 logging
 import optparse
 import os
 import sys
@@ skipping 147 matching lines @@
 For basic jank busting uses, use  --trace-frame-viewer
 For detailed study of ubercompositor, pass --trace-ubercompositor.
 
 When in doubt, just try out --trace-frame-viewer.
 """)
 
   if options.verbose:
     logging.getLogger().setLevel(logging.DEBUG)
 
   devices = android_commands.GetAttachedDevices()
-  if not options.device and len(devices) != 1:
-    parser.error('Exactly 1 device must be attached.')
-  device = device_utils.DeviceUtils(
-    next((d for d in devices if d == options.device), devices[0]))
+  device = None
+  if options.device in devices:
+    device = options.device
+  elif not options.device and len(devices) == 1:
+    device = devices[0]
+  if not device:
+    parser.error('Use -d/--device to select a device:\n' + '\n'.join(devices))
+  device = device_utils.DeviceUtils(device)
   package_info = profiler.GetSupportedBrowsers()[options.browser]
 
   if options.chrome_categories in ['list', 'help']:
     ui.PrintMessage('Collecting record categories list...', eol='')
     record_categories = []
     disabled_by_default_categories = []
     record_categories, disabled_by_default_categories = \
         chrome_controller.ChromeTracingController.GetCategories(
             device, package_info)
 
@@ skipping 60 matching lines @@
       enabled_controllers,
       options.time if not options.continuous else 0,
       output=options.output,
       compress=options.compress,
       write_json=options.json)
   if options.view:
     if sys.platform == 'darwin':
       os.system('/usr/bin/open %s' % os.path.abspath(result))
     else:
       webbrowser.open(result)