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 import system_health_story
+
+# Number of seconds to wait between backgrounding the browser and
+# measuring the memory use.
+PRE_MEASUREMENT_DELAY_SECONDS = 2
+
+class _BackgroundStory(system_health_story.SystemHealthStory):
+  """Abstract base class for background stories
+
+  As in _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()
+    action_runner.Wait(PRE_MEASUREMENT_DELAY_SECONDS)

[perezju, 2016/10/05 13:55:38]

Actually, no, sorry about that. The _Measure method will eventually call
MeasureMemory in deterministic_mode, and that will already include a wait.

https://cs.chromium.org/chromium/src/third_party/catapult/telemetry/telemetry...

[hjd, 2016/10/05 15:07:40]

Done.

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

[perezju, 2016/10/05 13:55:38]

My proposal would be to include:

- background:social:facebook
- background:search:google
- background:news:nytimes
- background:tools:gmail
- background:media:imgur

Details and rationale:
https://docs.google.com/a/google.com/document/d/1fQXX2W1qNdRSRWmVuhiFrDcyqxHV...

[hjd, 2016/10/05 15:07:40]

Done, except gmail which is a little tricky.

+