First cut of chrome-proxy (data reduction proxy) measurements.

tools/perf/metrics/loading.py

 # Copyright 2013 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 metrics import Metric
 
 class LoadingMetric(Metric):
   """A metric for page loading time based entirely on window.performance"""
 
   def Start(self, page, tab):
     raise NotImplementedError()
 
   def Stop(self, page, tab):
     raise NotImplementedError()
 
   def AddResults(self, tab, results):
     load_timings = tab.EvaluateJavaScript('window.performance.timing')
-    load_time_ms = (
-      float(load_timings['loadEventStart']) -
-      load_timings['navigationStart'])
-    dom_content_loaded_time_ms = (
+
+    # All numbers in milliseconds.

[tonyg, 2014/03/25 16:12:25]

Let's factor just this file out into a separate patch. It should be ready to
land with the nits below.

Sorry to be a pain about that, but the tiny patches make it so that if we break
or change existing tests then the problems are very easy to diagnose.

[bolian, 2014/03/25 18:19:01]

Done. Np at all, that is good.
Split out: https://codereview.chromium.org/199653007/

+    page_load = (
+      float(load_timings['loadEventStart']) - load_timings['navigationStart'])
+    results.Add('page_load', 'ms', page_load)

[tonyg, 2014/03/25 16:12:25]

Naming convention suggestion:

# NavigationStart relative markers end with "start":
'fetch_start'
'request_start'
'dom_content_loaded_start'
'window_load_start'

# Phase measurements end with "duration":
'domain_lookup_duration'
'connect_duration'
'request_duration'
'response_duration'

WDYT?

[bolian, 2014/03/25 18:19:01]

Doen. much better.

+
+    dom_content_loaded = (
       float(load_timings['domContentLoadedEventStart']) -
       load_timings['navigationStart'])
-    results.Add('load_time', 'ms', load_time_ms)
-    results.Add('dom_content_loaded_time', 'ms',
-                dom_content_loaded_time_ms)
+    results.Add('dom_content_loaded', 'ms', dom_content_loaded)
+
+    delay_before_fetch = (
+        float(load_timings['fetchStart']) - load_timings['navigationStart'])
+    results.Add('delay_before_fetch', 'ms', delay_before_fetch,
+                data_type='unimportant')
+
+    delay_before_request = (
+        float(load_timings['requestStart']) - load_timings['navigationStart'])
+    results.Add('delay_before_request', 'ms', delay_before_request,
+                data_type='unimportant')
+
+    domain_lookup = (
+        float(load_timings['domainLookupEnd']) -
+        load_timings['domainLookupStart'])
+    results.Add('domain_lookup', 'ms', domain_lookup, data_type='unimportant')
+
+    connect = (
+        float(load_timings['connectEnd']) - load_timings['connectStart'])
+    results.Add('connect', 'ms', connect, data_type='unimportant')
+
+    request = (
+        float(load_timings['responseStart']) - load_timings['requestStart'])
+    results.Add('request', 'ms', request, data_type='unimportant')
+
+    response = (
+        float(load_timings['responseEnd']) - load_timings['responseStart'])
+    results.Add('response', 'ms', response, data_type='unimportant')