Revert of [Telemetry] Overhaul startup metric.

tools/perf/metrics/startup_metric.py

Index: tools/perf/metrics/startup_metric.py
diff --git a/tools/perf/metrics/startup_metric.py b/tools/perf/metrics/startup_metric.py
index f5724674b101e98153d62db9ac4f81519f3eb211..1e742ee74024c12ee5222a4453ff9fc046d8ef06 100644
--- a/tools/perf/metrics/startup_metric.py
+++ b/tools/perf/metrics/startup_metric.py
@@ -1,32 +1,24 @@
 # 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.
-
+import collections
 import json
 import logging
 
+from metrics import Metric
 from metrics import histogram_util
-from metrics import Metric
+
 from telemetry.core import util
 
 
 class StartupMetric(Metric):
-  """A metric for browser startup time.
+  "A metric for browser startup time."
 
-  User visible metrics:
-    process_creation_to_window_display: Time from browser process creation to
-        the time that the browser window initially becomes visible.
-    process_creation_to_foreground_tab_loaded: Time from browser process
-        creation to the time that the foreground tab is fully loaded.
-    process_creation_to_all_tabs_loaded: Time from the browser process creation
-        to the time that all tabs have fully loaded.
-
-  Critical code progression:
-    process_creation_to_main: Time from process creation to the execution of the
-        browser's main() entry.
-    main_to_messageloop_start: Time from main() entry to the start of the UI
-        thread's message loop.
-  """
+  HISTOGRAMS_TO_RECORD = {
+    'messageloop_start_time' :
+        'Startup.BrowserMessageLoopStartTimeFromMainEntry',
+    'window_display_time' : 'Startup.BrowserWindowDisplay',
+    'open_tabs_time' : 'Startup.BrowserOpenTabs'}
 
   def Start(self, page, tab):
     raise NotImplementedError()
@@ -36,68 +28,86 @@
 
   def _GetBrowserMainEntryTime(self, tab):
     """Returns the main entry time (in ms) of the browser."""
+    histogram_type = histogram_util.BROWSER_HISTOGRAM
     high_bytes = histogram_util.GetHistogramSum(
-        histogram_util.BROWSER_HISTOGRAM,
+        histogram_type,
         'Startup.BrowserMainEntryTimeAbsoluteHighWord',
         tab)
     low_bytes = histogram_util.GetHistogramSum(
-        histogram_util.BROWSER_HISTOGRAM,
+        histogram_type,
         'Startup.BrowserMainEntryTimeAbsoluteLowWord',
         tab)
     if high_bytes == 0 and low_bytes == 0:
       return None
     return (int(high_bytes) << 32) | (int(low_bytes) << 1)
 
-  def _GetTabLoadTimes(self, browser):
-    """Returns a tuple of (foreground_tab_load_time, all_tabs_load_time)."""
-    foreground_tab_load_time = 0
-    all_tabs_load_time = 0
-    for i in xrange(len(browser.tabs)):
+  def _RecordTabLoadTimes(self, tab, browser_main_entry_time_ms, results):
+    """Records the tab load times for the browser. """
+    tab_load_times = []
+    TabLoadTime = collections.namedtuple(
+        'TabLoadTime',
+        ['load_start_ms', 'load_duration_ms'])
+
+    def RecordTabLoadTime(t):
       try:
-        tab = browser.tabs[i]
-        tab.WaitForDocumentReadyStateToBeComplete()
-        result = json.loads(tab.EvaluateJavaScript(
-            'statsCollectionController.tabLoadTiming()'))
-        load_time = result['load_start_ms'] + result['load_duration_ms']
-        all_tabs_load_time = max(all_tabs_load_time, load_time)
-        if tab == browser.foreground_tab:
-          foreground_tab_load_time = load_time
+        t.WaitForDocumentReadyStateToBeComplete()
+
+        result = t.EvaluateJavaScript(
+            'statsCollectionController.tabLoadTiming()')
+        result = json.loads(result)
+
+        if 'load_start_ms' not in result or 'load_duration_ms' not in result:
+          raise Exception("Outdated Chrome version, "
+              "statsCollectionController.tabLoadTiming() not present")
+        if result['load_duration_ms'] is None:
+          tab_title = t.EvaluateJavaScript('document.title')
+          print "Page: ", tab_title, " didn't finish loading."
+          return
+
+        tab_load_times.append(TabLoadTime(
+            int(result['load_start_ms']),
+            int(result['load_duration_ms'])))
       except util.TimeoutException:
         # Low memory Android devices may not be able to load more than
         # one tab at a time, so may timeout when the test attempts to
         # access a background tab. Ignore these tabs.
-        logging.error('Tab timed out on JavaScript access')
-    return foreground_tab_load_time, all_tabs_load_time
+        logging.error("Tab timed out on JavaScript access")
+
+    # Only measure the foreground tab. We can't measure all tabs on Android
+    # because on Android the data of the background tabs is loaded on demand,
+    # when the user switches to them, rather than during startup. In view of
+    # this, to get the same measures on all platform, we only measure the
+    # foreground tab on all platforms.
+
+    RecordTabLoadTime(tab.browser.foreground_tab)
+
+    foreground_tab_stats = tab_load_times[0]
+    foreground_tab_load_complete = ((foreground_tab_stats.load_start_ms +
+        foreground_tab_stats.load_duration_ms) - browser_main_entry_time_ms)
+    results.Add(
+        'foreground_tab_load_complete', 'ms', foreground_tab_load_complete)
 
   def AddResults(self, tab, results):
-    absolute_browser_main_entry_ms = self._GetBrowserMainEntryTime(tab)
+    get_histogram_js = 'statsCollectionController.getBrowserHistogram("%s")'
 
-    process_creation_to_window_display_ms = histogram_util.GetHistogramSum(
-        histogram_util.BROWSER_HISTOGRAM, 'Startup.BrowserWindowDisplay', tab)
-    absolute_foreground_tab_loaded_ms, absolute_all_tabs_loaded_ms = \
-        self._GetTabLoadTimes(tab.browser)
-    process_creation_to_messageloop_start_ms = histogram_util.GetHistogramSum(
-        histogram_util.BROWSER_HISTOGRAM, 'Startup.BrowserMessageLoopStartTime',
-        tab)
-    main_to_messageloop_start_ms = histogram_util.GetHistogramSum(
-        histogram_util.BROWSER_HISTOGRAM,
-        'Startup.BrowserMessageLoopStartTimeFromMainEntry',
-        tab)
-    process_creation_to_main = (process_creation_to_messageloop_start_ms -
-                                main_to_messageloop_start_ms)
+    for display_name, histogram_name in self.HISTOGRAMS_TO_RECORD.iteritems():
+      result = tab.EvaluateJavaScript(get_histogram_js % histogram_name)
+      result = json.loads(result)
+      measured_time = 0
 
-    # User visible.
-    results.Add('process_creation_to_window_display', 'ms',
-                process_creation_to_window_display_ms)
-    results.Add('process_creation_to_foreground_tab_loaded', 'ms',
-                absolute_foreground_tab_loaded_ms -
-                absolute_browser_main_entry_ms + process_creation_to_main)
-    results.Add('process_creation_to_all_tabs_loaded', 'ms',
-                absolute_all_tabs_loaded_ms -
-                absolute_browser_main_entry_ms + process_creation_to_main)
+      if 'sum' in result:
+        # For all the histograms logged here, there's a single entry so sum
+        # is the exact value for that entry.
+        measured_time = result['sum']
+      elif 'buckets' in result:
+        measured_time = \
+            (result['buckets'][0]['high'] + result['buckets'][0]['low']) / 2
 
-    # Critical code progression.
-    results.Add('process_creation_to_main', 'ms',
-                process_creation_to_main)
-    results.Add('main_to_messageloop_start', 'ms',
-                main_to_messageloop_start_ms)
+      results.Add(display_name, 'ms', measured_time)
+
+    # Get tab load times.
+    browser_main_entry_time_ms = self._GetBrowserMainEntryTime(tab)
+    if (browser_main_entry_time_ms is None):
+      print "Outdated Chrome version, browser main entry time not supported."
+      return
+    self._RecordTabLoadTimes(tab, browser_main_entry_time_ms, results)