[memory-infra] Add DumpStateUponFailure method to MultiBrowserSharedState

tools/perf/page_sets/dual_browser_story.py

 # Copyright 2016 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 collections
 import logging
 import re
 import sys
 import urllib
 
@@ skipping 172 matching lines @@
   def TearDownState(self):
     self.platform.network_controller.Close()
 
     for browser_type, browser in self._browsers.iteritems():
       try:
         browser.Close()
       except Exception:
         logging.exception('Error while closing browser: %s', browser_type)
     self._browsers = None  # Not usable after tearing down.
 
+  def DumpStateUponFailure(self, unused_story, unused_results):
+    if self._browsers:
+      for browser_type, browser in self._browsers.iteritems():
+        logging.info('vvvvv BROWSER STATE BELOW FOR \'%s\' vvvvv', browser_type)
+        browser.DumpStateUponFailure()
+    else:
+      logging.warning('Cannot dump browser states: No browsers.')
+
 
 class SinglePage(story_module.Story):
   def __init__(self, name, url, browser_type, phase):
     """A story that associates a particular page with a browser to view it.
 
     Args:
       name: A string with the name of the page as it will appear reported,
         e.g., on results and dashboards.
       url: A string with the url of the page to load.
       browser_type: A string identifying the browser where this page should be
@@ skipping 35 matching lines @@
           url=GOOGLE_SEARCH + urllib.urlencode({'q': query}),
           browser_type='android-webview',
           phase='on_webview'))
 
       # Stories that run on the browser selected by command line options.
       self.AddStory(SinglePage(
           name=re.sub('\W+', '_', url),
           url=url,
           browser_type='default',
           phase='on_chrome'))