Increase default DevTools request timeout to 30 seconds.

tools/telemetry/telemetry/core/backends/chrome/chrome_browser_backend.py

 # Copyright 2013 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 contextlib
 import httplib
 import json
 import logging
 import pprint
 import re
@@ skipping 176 matching lines @@
       except util.TimeoutException:
         logging.error('ExtensionsToLoad: ' +
             repr([e.extension_id for e in self._extensions_to_load]))
         logging.error('Extension list: ' +
             pprint.pformat(self.extension_backend, indent=4))
         raise
 
   def ListInspectableContexts(self):
     return json.loads(self.Request(''))
 
-  def Request(self, path, timeout=5, throw_network_exception=False):
+  def Request(self, path, timeout=30, throw_network_exception=False):
     url = 'http://127.0.0.1:%i/json' % self._port
     if path:
       url += '/' + path
     try:
       proxy_handler = urllib2.ProxyHandler({})  # Bypass any system proxy.
       opener = urllib2.build_opener(proxy_handler)
       with contextlib.closing(opener.open(url, timeout=timeout)) as req:
         return req.read()
     except (socket.error, httplib.BadStatusLine, urllib2.URLError) as e:
       if throw_network_exception:
@@ skipping 104 matching lines @@
 
   @property
   def supports_system_info(self):
     return self.GetSystemInfo() != None
 
   def GetSystemInfo(self):
     if self._system_info_backend is None:
       self._system_info_backend = system_info_backend.SystemInfoBackend(
           self._port)
     return self._system_info_backend.GetSystemInfo()