Move top_20 tests to a separate suite

tools/chrome_proxy/common/chrome_proxy_benchmark.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 common import chrome_proxy_measurements as measurements
+from telemetry import benchmark
+
+
+class ChromeProxyBenchmark(benchmark.Benchmark):
+  @classmethod
+  def AddCommandLineArgs(cls, parser):
+    parser.add_option(
+        '--extra-chrome-proxy-via-header',
+        type='string', dest="extra_header",
+        help='Adds an expected Via header for the Chrome-Proxy tests.')
+
+  @classmethod
+  def ProcessCommandLineArgs(cls, parser, args):
+    if args.extra_header:
+      measurements.ChromeProxyValidation.extra_via_header = args.extra_header
+