Introduce --cancel-first-run and reduce the strength of --no-first-run.

ppapi/native_client/tools/browser_tester/browsertester/browserlauncher.py

 #!/usr/bin/python
 # Copyright (c) 2012 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 os.path
 import re
 import shutil
 import sys
 import tempfile
@@ skipping 257 matching lines @@
             # it actually turns off logging to the Buildbot logs on
             # Windows (see http://crbug.com/169941).
             '--disable-web-resources',
             '--disable-preconnect',
             # This is speculative, sync should not occur with a clean profile.
             '--disable-sync',
             # This prevents Chrome from making "hidden" network requests at
             # startup.  These requests could be a source of non-determinism,
             # and they also add noise to the netlogs.
             '--dns-prefetch-disable',
-            '--no-first-run',
+            '--skip-first-run',
             '--no-default-browser-check',
             '--log-level=1',
             '--safebrowsing-disable-auto-update',
             # Suppress metrics reporting.  This prevents misconfigured bots,
             # people testing at their desktop, etc from poisoning the UMA data.
             '--metrics-recording-only',
             # Chrome explicitly blacklists some ports as "unsafe" because
             # certain protocols use them.  Chrome gives an error like this:
             # Error 312 (net::ERR_UNSAFE_PORT): Unknown error
             # Unfortunately, the browser tester can randomly choose a
@@ skipping 42 matching lines @@
              '--trace-children=yes',
              '--nacl-file=%s' % (self.options.files[0],),
              '--ignore=../tools/valgrind/tsan/ignores.txt',
              '--suppressions=../tools/valgrind/tsan/suppressions.txt',
              '--log-file=%s/log.%%p' % (self.tool_log_dir,)] + cmd
     elif self.options.tool != None:
       raise LaunchFailure('Invalid tool name "%s"' % (self.options.tool,))
     cmd.extend(self.options.browser_flags)
     cmd.append(url)
     return cmd