Add --passthrough command line arg for Telemetry-based GPU tests.

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 2287 matching lines @@
     result['precommit_args'] = test_config['precommit_args']
   return result
 
 def generate_telemetry_test(tester_name, tester_config,
                             test, test_config):
   extra_browser_args = ['--enable-logging=stderr', '--js-flags=--expose-gc']
   benchmark_name = test_config.get('target_name') or test
   prefix_args = [
     benchmark_name,
     '--show-stdout',
-    '--browser=%s' % tester_config['build_config'].lower()
+    '--browser=%s' % tester_config['build_config'].lower(),
+    # --passthrough displays more of the logging in Telemetry when run
+    # --via typ, in particular some of the warnings about tests being
+    # --expected to fail, but passing.
+    '--passthrough',
   ]
   return generate_isolated_test(tester_name, tester_config, test,
                                 test_config, extra_browser_args,
                                 'telemetry_gpu_integration_test',
                                 ['telemetry_gpu_integration_test'],
                                 prefix_args)
 
 def generate_telemetry_tests(tester_name, tester_config,
                              test_dictionary):
   isolated_scripts = []
@@ skipping 55 matching lines @@
   install_parent_links(WATERFALL)
   install_parent_links(V8_FYI_WATERFALL)
 
   generate_all_tests(FYI_WATERFALL, 'chromium.gpu.fyi.json')
   generate_all_tests(WATERFALL, 'chromium.gpu.json')
   generate_all_tests(V8_FYI_WATERFALL, 'client.v8.fyi.json')
   return 0
 
 if __name__ == "__main__":
   sys.exit(main())