Implemented telemetry benchmark that loads page and outputs screenshot.

tools/perf/contrib/cluster_telemetry/pixel_diff_ct.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.
+
+from core import perf_benchmark
+
+from contrib.cluster_telemetry import ct_benchmarks_util
+from contrib.cluster_telemetry import page_set
+from contrib.cluster_telemetry import repaint_helpers
+
+from measurements import pixel_diff
+
+class PixelDiffCT(perf_benchmark.PerfBenchmark):

[nednguyen, 2017/06/07 20:32:12]

This should inherit s.t like a base CTBenchmark class so you have less boiler
plate to fill out

[wkorman, 2017/06/08 17:57:52]

Looks reasonable to me, but propose doing as separate patch as it's essentially
a code maintenance/sharing cleanup work item.

+  """Captures PNG screenshots of web pages for Cluster Telemetry."""

[wkorman, 2017/06/07 20:15:11]

Consider adding note that we write to a local file with filename turned into
path-safe url, and that we rely on CT to aggregate.

+
+  @classmethod
+  def Name(cls):
+    return 'pixel_diff_ct'
+
+  @classmethod
+  def AddBenchmarkCommandLineArgs(cls, parser):
+    ct_benchmarks_util.AddBenchmarkCommandLineArgs(parser)
+    parser.add_option('--png-outdir', type='string',
+                      default=None,
+                      help='Output directory for the PNG files')
+    parser.add_option('--wait-time', type='float', default=0,
+                      help='Wait time before the benchmark is started')
+    parser.add_option('--disable-javascript', action='store_true',

[wkorman, 2017/06/07 20:15:11]

Either remove for now or clarify that this is planned but not yet implemented in
the description.

+                      default=False,
+                      help='Strips out script tags from page if enabled')
+
+  @classmethod
+  def ProcessCommandLineArgs(cls, parser, args):
+    ct_benchmarks_util.ValidateCommandLineArgs(parser, args)
+    if not args.png_outdir:
+      parser.error('Please specify --png-outdir')
+
+  def CreatePageTest(self, options):
+    return pixel_diff.PixelDiff(options.png_outdir)
+
+  def CreateStorySet(self, options):
+    return page_set.CTPageSet(
+        options.urls_list, options.user_agent, options.archive_data_file,
+        run_page_interaction_callback=repaint_helpers.WaitThenRepaint)