chromecast: trace.py: Turn on system tracing by default

Now that we have compression enabled, system tracing doesn't cause
flakes due to filling up /tmp, and we should be able to safely turn
it on by default.

Also increase the websocket timeout, since very large traces might take
more than 10s to compress.

BUG=786091
TEST=trace.py

Change-Id: I65726a723eb4b28466f4bff0dd818db916165227
Reviewed-on: https://chromium-review.googlesource.com/830916Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: Michael Spang <spang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524612}

chromecast/tools/trace.py

@@ -22,7 +22,7 @@ def Connect(options):
   if options.adb_device:
     backend = TracingBackendAndroid(options.adb_device)
   else:
-    backend = TracingBackend(options.device, options.port, 10, 0)
+    backend = TracingBackend(options.device, options.port, options.timeout, 0)
 
   try:
     backend.Connect()
@@ -57,6 +57,9 @@ def _CreateOptionParser():
       default='127.0.0.1')
   parser.add_option(
       '-s', '--adb-device', help='Device serial for adb.', type='string')
+  parser.add_option(
+      '-t', '--timeout', help='Websocket timeout interval.', type='int',
+      default=90)
 
   tracing_opts = optparse.OptionGroup(parser, 'Tracing options')
   tracing_opts.add_option(
@@ -75,7 +78,7 @@ def _CreateOptionParser():
       help='Enable system tracing.',
       action='store_true',
       dest='systrace',
-      default=False)
+      default=True)
   parser.add_option_group(tracing_opts)
 
   output_options = optparse.OptionGroup(parser, 'Output options')