Enable extra flags to make sure that C++ perf tests always output metrics

testing/scripts/run_gtest_perf_test.py

 #!/usr/bin/env python
 # Copyright 2015 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 an isolated non-Telemetry perf test .
 
 The main contract is that the caller passes the arguments:
 
   --isolated-script-test-output=[FILENAME]
@@ skipping 70 matching lines @@
                                                              build_dir='.')
     assert xvfb_proc and openbox_proc and xcompmgr_proc, 'Failed to start xvfb'
 
   try:
     rc = 0
     try:
       executable = rest_args[0]
       extra_flags = []
       if len(rest_args) > 1:
         extra_flags = rest_args[1:]
+
+      # These flags are to make sure that test output perf metrics in the log.
+      if not '--verbose' in extra_flags:
+        extra_flags.append('--verbose')
+      if not '--test-launcher-print-test-stdio=always' in extra_flags:
+        extra_flags.append('--test-launcher-print-test-stdio=always')
+
       if IsWindows():
         executable = '.\%s.exe' % executable
       else:
         executable = './%s' % executable
       with common.temporary_file() as tempfile_path:
         rc = common.run_command_with_output([executable] + extra_flags,
             env=env, stdoutfile=tempfile_path)
         with open(tempfile_path) as f:
           print f.read()
 
@@ skipping 34 matching lines @@
 if __name__ == '__main__':
   # Conform minimally to the protocol defined by ScriptTest.
   if 'compile_targets' in sys.argv:
     funcs = {
       'run': None,
       'compile_targets': main_compile_targets,
     }
     sys.exit(common.run_script(sys.argv[1:], funcs))
   sys.exit(main())