Specify --test-machine-name to maps_pixel_test running on bots.

content/test/gpu/generate_buildbot_json.py

 #!/usr/bin/env python
 # Copyright 2016 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.
 
 """Script to generate chromium.gpu.json and chromium.gpu.fyi.json in
 the src/testing/buildbot directory. Maintaining these files by hand is
 too unwieldy.
 """
 
@@ skipping 726 matching lines @@
   },
   'hardware_accelerated_feature': {
     'tester_configs': [
       {
         'allow_on_android': True,
       },
     ],
   },
   'maps_pixel_test': {
     'target_name': 'maps',
+    'args': [
+      '--os-type',
+      '${os_type}',
+      '--build-revision',
+      '${got_revision}',
+      '--test-machine-name',
+      '${buildername}',
+    ],
     'tester_configs': [
       {
         'allow_on_android': True,
       },
     ],
   },
   'memory_test': {
     'tester_configs': [
       {
         'allow_on_android': True,
@@ skipping 371 matching lines @@
     json.dump(tests, fp, indent=2, separators=(',', ': '), sort_keys=True)
     fp.write('\n')
 
 def main():
   generate_all_tests(FYI_WATERFALL, True)
   generate_all_tests(WATERFALL, False)
   return 0
 
 if __name__ == "__main__":
   sys.exit(main())