Add background stories to MobileSystemHealth

tools/perf/page_sets/system_health/background_stories.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.
+
+from page_sets.system_health import platforms
+from page_sets.system_health.loading_stories import _LoadingStory
+from page_sets.system_health.loading_stories import _LoadGmailBaseStory
+
+class _BackgroundStoryMixin(object):
+  """Mixin class for background stories
+
+  Overrides _Measure to put the browser into the background before measuring.
+  """
+
+  def _Measure(self, action_runner):
+    action_runner.tab.browser.Background()
+    super(_BackgroundStoryMixin, self)._Measure(action_runner)
+
+
+class BackgroundGoogleStory(_LoadingStory, _BackgroundStoryMixin):
+  NAME = 'background:search:google'
+  URL = 'https://www.google.co.uk/#q=tom+cruise+movies'
+  SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
+
+  def _DidLoadDocument(self, action_runner):
+    # Activte the immersive movie browsing experience
+    action_runner.WaitForJavaScriptCondition(
+        'document.querySelector("g-fab") !== null')
+    action_runner.ExecuteJavaScript(
+        'document.querySelector("g-fab").click()')
+
+
+class BackgroundFacebookMobileStory(_LoadingStory, _BackgroundStoryMixin):
+  NAME = 'background:social:facebook'
+  URL = 'https://www.facebook.com/rihanna'
+  SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
+
+
+class BackgroundNytimesMobileStory(_LoadingStory, _BackgroundStoryMixin):
+  """The third top website in http://www.alexa.com/topsites/category/News"""
+  NAME = 'background:news:nytimes'
+  URL = 'http://www.nytimes.com/2016/10/04/us/politics/vice-presidential-debate.html?_r=0'
+  SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
+
+
+class BackgroundImgurMobileStory(_LoadingStory, _BackgroundStoryMixin):
+  NAME = 'background:media:imgur'
+  URL = 'http://imgur.com/gallery/hUita'
+  SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
+
+
+# pylint: disable=too-many-ancestors
+class BackgroundGmailMobileStory(_LoadGmailBaseStory, _BackgroundStoryMixin):

[perezju, 2016/10/06 12:41:45]

I'm not super excited about the multiple inheritance, it tends to get kind of
confusing quickly.

Can we keep all other stories as in your patch set #7; and then for the gmail
case subclass the public LoadGmailMobileStory and override methods as needed?
(Even if it leads to a bit of code duplication, it would be easier to
understand).

+  NAME = 'background:tools:gmail'
+  SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
+
+  def _DidLoadDocument(self, action_runner):
+    pass
+
+