Revert of Update systrace and profile_chrome's default agent behavior

systrace/profile_chrome/chrome_tracing_agent.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.
 
 import json
 import optparse
 import os
 import py_utils
 import re
 
 from devil.android import device_errors
 from devil.android.sdk import intent
 from systrace import trace_result
 from systrace import tracing_agents
 
 
-DEFAULT_CHROME_CATEGORIES = '_DEFAULT_CHROME_CATEGORIES'
+_DEFAULT_CHROME_CATEGORIES = '_DEFAULT_CHROME_CATEGORIES'
 _HEAP_PROFILE_MMAP_PROPERTY = 'heapprof.mmap'
 
 
 class ChromeTracingAgent(tracing_agents.TracingAgent):
   def __init__(self, device, package_info, ring_buffer, trace_memory=False):
     tracing_agents.TracingAgent.__init__(self)
     self._device = device
     self._package_info = package_info
     self._ring_buffer = ring_buffer
     self._logcat_monitor = self._device.GetLogcatMonitor()
@@ skipping 128 matching lines @@
   return None
 
 def add_options(parser):
   chrome_opts = optparse.OptionGroup(parser, 'Chrome tracing options')
   chrome_opts.add_option('-c', '--categories', help='Select Chrome tracing '
                          'categories with comma-delimited wildcards, '
                          'e.g., "*", "cat1*,-cat1a". Omit this option to trace '
                          'Chrome\'s default categories. Chrome tracing can be '
                          'disabled with "--categories=\'\'". Use "list" to '
                          'see the available categories.',
-                         metavar='CHROME_CATEGORIES', dest='chrome_categories')
+                         metavar='CHROME_CATEGORIES', dest='chrome_categories',
+                         default=_DEFAULT_CHROME_CATEGORIES)
   chrome_opts.add_option('--trace-cc',
                          help='Deprecated, use --trace-frame-viewer.',
                          action='store_true')
   chrome_opts.add_option('--trace-frame-viewer',
                          help='Enable enough trace categories for '
                          'compositor frame viewing.', action='store_true')
   chrome_opts.add_option('--trace-ubercompositor',
                          help='Enable enough trace categories for '
                          'ubercompositor frame data.', action='store_true')
   chrome_opts.add_option('--trace-gpu', help='Enable extra trace categories '
@@ skipping 28 matching lines @@
     categories.append('disabled-by-default-toplevel.flow')
   if config.trace_memory:
     categories.append('disabled-by-default-memory')
   if config.trace_scheduler:
     categories.append('disabled-by-default-blink.scheduler')
     categories.append('disabled-by-default-cc.debug.scheduler')
     categories.append('disabled-by-default-renderer.scheduler')
   if config.chrome_categories:
     categories += config.chrome_categories.split(',')
   return categories