[Telemetry] Measure power in tab_switching measurement

tools/perf/benchmarks/power.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.
+from telemetry import test
+
+from measurements import power_many_tabs
+
+
+# Only enabled on systems that allow power measurement.
+@test.Enabled('mavericks')
+class BlankTabs(test.Test):
+  """Load 5 blank tabs and measure power usage."""
+  tag = 'five_blank_tabs'
+  test = power_many_tabs.PowerManyTabs
+  page_set = 'page_sets/five_blank_pages.json'
+  options = {'pageset_repeat_iters': 5}