[Android] Add option to run perf tests in platform mode.

scripts/slave/recipe_modules/chromium_android/example.py

 # 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.
 
 from recipe_engine.types import freeze
 
 DEPS = [
     'adb',
     'chromium',
     'chromium_android',
@@ skipping 80 matching lines @@
       'device_flags': 'device_flags_file',
     },
     'no_cache_builder': {
       'use_git_cache': False,
     },
     'json_results_file': {
       'json_results_file': 'json_results_file'
     },
     'result_details': {
       'result_details': True
+    },
+    'enable_platform_mode': {
+      'perf_config': 'sharded_perf_tests.json',
+      'enable_platform_mode': True
     }
 })
 
 from recipe_engine.recipe_api import Property
 
 PROPERTIES = {
   'buildername': Property(),
 }
 
 def RunSteps(api, buildername):
@@ skipping 67 matching lines @@
     api.chromium_android.adb_install_apk('apk', allow_downgrade=True)
 
   api.chromium_android.monkey_test()
 
   try:
     if config.get('perf_config'):
       api.chromium_android.run_sharded_perf_tests(
           config='fake_config.json',
           flaky_config='flake_fakes.json',
           upload_archives_to_bucket='archives-bucket',
-          known_devices_file=config.get('last_known_devices', None))
+          known_devices_file=config.get('last_known_devices', None),
+          enable_platform_mode=config.get('enable_platform_mode', None))
   except api.step.StepFailure as f:
     failure = f
 
   api.chromium_android.run_instrumentation_suite(
       name='AndroidWebViewTest',
       apk_under_test=api.chromium_android.apk_path('AndroidWebView.apk'),
       test_apk=api.chromium_android.apk_path('AndroidWebViewTest.apk'),
       isolate_file_path='android_webview/android_webview_test_data.isolate',
       flakiness_dashboard='test-results.appspot.com',
       annotation='SmallTest',
@@ skipping 194 matching lines @@
 
   yield (api.test('device_file_format_mismatch') +
          properties_for('tester') +
          api.override_step_data('fix_device_file_format.read_device_file', 
              api.raw_io.output('["device1", "device2"]')))
 
   yield (api.test('tombstones_m53') +
          properties_for('tester') +
          api.override_step_data('get version (2)',
              api.raw_io.output('MAJOR=53\nMINOR=0\nBUILD=2800\nPATCH=0\n')))