Add live test for measuring data savings metrics

These tests will run against the same content each time, which will allow
us to track any change in data savings at a very detailed level.

BUG=573035

Review URL: https://codereview.chromium.org/1556593002

Cr-Commit-Position: refs/heads/master@{#367129}

tools/chrome_proxy/live_tests/chrome_proxy_benchmark.py

@@ -27,6 +27,16 @@ class ChromeProxyLatencyDirect(benchmark.Benchmark):
     return 'chrome_proxy_benchmark.latency_direct.top_20'
 
 
+class ChromeProxyLatencyMetrics(benchmark.Benchmark):
+  tag = 'latency_metrics'
+  test = measurements.ChromeProxyLatencyDirect
+  page_set = pagesets.MetricsStorySet
+
+  @classmethod
+  def Name(cls):
+    return 'chrome_proxy_benchmark.latency_metrics.metrics'
+
+
 class ChromeProxyDataSaving(benchmark.Benchmark):
   tag = 'data_saving'
   test = measurements.ChromeProxyDataSaving
@@ -46,3 +56,12 @@ class ChromeProxyDataSavingDirect(benchmark.Benchmark):
   def Name(cls):
     return 'chrome_proxy_benchmark.data_saving_direct.top_20'
 
+class ChromeProxyDataSavingMetrics(benchmark.Benchmark):
+  tag = 'data_saving_metrics'
+  test = measurements.ChromeProxyDataSavingDirect
+  page_set = pagesets.MetricsStorySet
+
+  @classmethod
+  def Name(cls):
+    return 'chrome_proxy_benchmark.data_saving_metrics.metrics'
+

tools/chrome_proxy/live_tests/pagesets/metrics.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.page import page as page_module
+from telemetry import story
+
+
+class MetricsPage(page_module.Page):
+
+  def __init__(self, url, page_set):
+    super(MetricsPage, self).__init__(url=url, page_set=page_set)
+
+
+class MetricsStorySet(story.StorySet):
+
+  """ Chrome proxy test sites for measuring data savings """
+
+  def __init__(self):
+    super(MetricsStorySet, self).__init__()
+
+    urls_list = [
+      'http://check.googlezip.net/metrics/',
+    ]
+
+    for url in urls_list:
+      self.AddStory(MetricsPage(url, self))