Add background stories to MobileSystemHealth

tools/perf/page_sets/system_health/background_stories.py

Index: tools/perf/page_sets/system_health/background_stories.py
diff --git a/tools/perf/page_sets/system_health/background_stories.py b/tools/perf/page_sets/system_health/background_stories.py
new file mode 100644
index 0000000000000000000000000000000000000000..c129876290600033e7cc837de36eff7477e706db
--- /dev/null
+++ b/tools/perf/page_sets/system_health/background_stories.py
@@ -0,0 +1,26 @@
+# 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 import system_health_story
+
+class _BackgroundStory(system_health_story.SystemHealthStory):
+  """Abstract base class for background stories
+
+  As a _LoadingStory except it puts the browser into the
+  background before measuring.
+  """
+  ABSTRACT_STORY = True
+  SUPPORTED_PLATFORMS = platforms.MOBILE_ONLY
+
+  def _Measure(self, action_runner):
+    action_runner.tab.browser.Background()

[nednguyen, 2016/10/05 13:10:49]

Should we wait few seconds after backgrounding to measure memory?

[perezju, 2016/10/05 13:14:54]

+1

[hjd, 2016/10/05 13:45:44]

Sounds good; 2 seconds?

+    super(_BackgroundStory, self)._Measure(action_runner)
+    action_runner.tab.browser.Foreground()

[nednguyen, 2016/10/05 13:10:49]

What happens if we don't foreground here? Would the next telemetry test run
fails?

[perezju, 2016/10/05 13:14:54]

I agree, we probably don't need to "Foreground" again; because the browser will
be closed/restarted before going to the next page.

[hjd, 2016/10/05 13:45:44]

Yep the restart brings up the browser again :) Shall I go ahead and remove this?

+
+
+class BackgroundGoogleStory(_BackgroundStory):
+  NAME = 'background:search:google'
+  URL = 'https://www.google.co.uk/'

[nednguyen, 2016/10/05 13:10:50]

Given that we only have around 5 single page stories for background, I am not
sure whether we should pick google.co.uk

[perezju, 2016/10/05 13:14:54]

I'm coming up with a list of stories to pick. Will share it in a few more
minutes.

+