[Telemetry] Measure power in tab_switching measurement

tools/perf/measurements/power_many_tabs.py

+# Copyright 2014 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 time
+
+from metrics import power
+from metrics import speedindex
+from telemetry.core import util
+from telemetry.page import page_measurement
+
+
+class PowerManyTabs(page_measurement.PageMeasurement):
+  """Open several blank tabs, measure power after quiesencence."""

[tonyg, 2014/02/27 06:42:17]

This shouldn't talk about blank tabs. The page set defines that.

[jeremy, 2014/02/27 13:41:12]

Makes sense, added a five_blank_tabs pageset.

+  # Total number of tabs to open.
+  NUM_TABS = 5

[tonyg, 2014/02/27 06:42:17]

Should this be equal to the number of pages in the page set?

[jeremy, 2014/02/27 13:41:12]

Done.

+
+  # Amount of time to measure power usage for, in seconds.
+  POWER_MEAUSUREMENT_TIME_S = 5
+
+  def __init__(self, action_name_to_run=''):
+    super(PowerManyTabs, self).__init__(
+                                  needs_browser_restart_after_each_run=True,
+                                  action_name_to_run=action_name_to_run)
+    self._power_metric = power.PowerMetric()
+
+    # This metric is not measured, we just use it's functionality to ascertain
+    # load completion.

[tonyg, 2014/02/27 06:42:17]

Like we talked about offline, I recommend factoring out a WaitForQuiescence()
method here:
https://code.google.com/p/chromium/codesearch#chromium/src/tools/telemetry/te...

And then both SpeedIndex and this would invoke it.

+    self._speedindex_metric = speedindex.SpeedIndexMetric()
+
+  def CustomizeBrowserOptions(self, options):
+    power.PowerMetric.CustomizeBrowserOptions(options)
+
+  def MeasurePage(self, page, tab, results):
+    for _ in xrange(PowerManyTabs.NUM_TABS - 1):
+      tab.browser.tabs.New()
+
+    def SpeedIndexIsFinished():
+      return self._speedindex_metric.IsFinished(tab)

[jeremy, 2014/02/25 15:05:00]

I'm not comfortable using speedindex like this, do you think I should split the
IsFinished() code out of speed index? - if so where should I put it?

If not, what would you prefer I do here?

[qsr, 2014/02/25 15:11:15]

Any reason to use speed index instead of usual page load? Or is it the same
thing in this context?

+    util.WaitFor(SpeedIndexIsFinished, 60)
+
+    # Measure power after quiescence.
+    self._power_metric.Start(page, tab)
+    time.sleep(PowerManyTabs.POWER_MEAUSUREMENT_TIME_S)
+    self._power_metric.Stop(page, tab)
+
+    self._power_metric.AddResults(tab, results)