Add a --startup option to generate combined traces for startup.

tools/profile_chrome/flags.py

+# 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.
+
+import optparse
+
+def SystraceOptions(parser):
+  systrace_opts = optparse.OptionGroup(parser, 'Systrace tracing options')
+  systrace_opts.add_option('-s', '--systrace', help='Capture a systrace with '
+                           'the chosen comma-delimited systrace categories. You'
+                           ' can also capture a combined Chrome + systrace by '
+                           'enable both types of categories. Use "list" to see '
+                           'the available categories. Systrace is disabled by '
+                           'default.', metavar='SYS_CATEGORIES',
+                           dest='systrace_categories', default='')
+  return systrace_opts
+
+
+def OutputOptions(parser):
+  output_options = optparse.OptionGroup(parser, 'Output options')
+  output_options.add_option('-o', '--output', help='Save trace output to file.')
+  output_options.add_option('--json', help='Save trace as raw JSON instead of '
+                            'HTML.', action='store_true')
+  output_options.add_option('--view', help='Open resulting trace file in a '
+                            'browser.', action='store_true')
+  return output_options