Tab Switching Benchmark for ChromeOS

tools/perf/contrib/cros_benchmarks/tab_switching_measure.py

+# Copyright 2017 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.
+
+"""The tab switching measurement.
+
+This measurement record the MPArch.RWH_TabSwitchPaintDuration histogram
+of each tab swithcing.
+"""
+
+from telemetry.page import legacy_page_test
+from telemetry.value import histogram
+from telemetry.value import histogram_util
+
+from contrib.cros_benchmarks import cros_utils
+
+
+class CrosTabSwitchingMeasurement(legacy_page_test.LegacyPageTest):
+  def __init__(self):
+    super(CrosTabSwitchingMeasurement, self).__init__()
+    self._first_histogram = None
+
+  def CustomizeBrowserOptions(self, options):
+    """Adding necessary browser flag to collect histogram."""
+    options.AppendExtraBrowserArgs(['--enable-stats-collection-bindings'])
+
+  def DidNavigateToPage(self, page, tab):
+    """Record the starting histogram."""
+    self._first_histogram = cros_utils.GetTabSwitchHistogramRetry(tab.browser)
+
+  def ValidateAndMeasurePage(self, page, tab, results):
+    """Record the ending histogram for the tab switching metric."""
+    last_histogram = cros_utils.GetTabSwitchHistogramRetry(tab.browser)
+    total_diff_histogram = histogram_util.SubtractHistogram(last_histogram,

[deanliao_goog, 2017/05/23 08:54:26]

Wrapping indentation: either aligned, e.g.

SomeFunction(arg1,
             arg2)

or wrap all args with 4 space indent:
SomeFunction(
    arg1, arg2)

+                            self._first_histogram)
+
+    display_name = 'MPArch_RWH_TabSwitchPaintDuration'
+    results.AddSummaryValue(
+        histogram.HistogramValue(None, display_name, 'ms',
+            raw_value_json=total_diff_histogram,
+            important=False))