Implements AddStartupEventsForTelemetry() in startup_metric_utils.cc for in-coming startup telemetry

components/startup_metric_utils/browser/startup_metric_utils.cc

 // 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.
 
 #include "components/startup_metric_utils/browser/startup_metric_utils.h"
 
 #include "base/containers/hash_tables.h"
 #include "base/environment.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
@@ skipping 296 matching lines @@
 
   const base::TimeDelta browser_main_entry_time_raw_ms_high_word =
       base::TimeDelta::FromMilliseconds(
           (browser_main_entry_time_raw_ms >> 32) & kLowWordMask);
   // Shift by one because histograms only support non-negative values.
   const base::TimeDelta browser_main_entry_time_raw_ms_low_word =
       base::TimeDelta::FromMilliseconds(
           (browser_main_entry_time_raw_ms >> 1) & kLower31BitsMask);
 
   // A timestamp is a 64 bit value, yet histograms can only store 32 bits.
+  // TODO(gabadie): Once startup_with_url.* benchmarks are replaced by

[gab, 2015/11/12 14:41:38]

Please add bug#

[gabadie, 2015/11/12 17:43:34]

Done.

+  //    startup_with_url2.*, remove this dirty hack.
   LOCAL_HISTOGRAM_TIMES("Startup.BrowserMainEntryTimeAbsoluteHighWord",
       browser_main_entry_time_raw_ms_high_word);
   LOCAL_HISTOGRAM_TIMES("Startup.BrowserMainEntryTimeAbsoluteLowWord",
       browser_main_entry_time_raw_ms_low_word);
 }
 
 // Environment variable that stores the timestamp when the executable's main()
 // function was entered in TimeTicks. This is required because chrome.exe and
 // chrome.dll don't share the same static storage.
 const char kChromeMainTicksEnvVar[] = "CHROME_MAIN_TICKS";
 
 // Returns the time of main entry recorded from RecordExeMainEntryTime.
 base::TimeTicks ExeMainEntryPointTicks() {
   scoped_ptr<base::Environment> env(base::Environment::Create());
   std::string ticks_string;
   int64 time_int = 0;
   if (env->GetVar(kChromeMainTicksEnvVar, &ticks_string) &&
       base::StringToInt64(ticks_string, &time_int)) {
     return base::TimeTicks::FromInternalValue(time_int);
   }
   return base::TimeTicks();
 }
 
+// Records "instant" trace events for global timings observed by telemetry.
+void AddStartupEventsForTelemetry() {
+  DCHECK(!g_process_creation_ticks.Get().is_null());
+  DCHECK(!g_main_entry_point_ticks.Get().is_null());
+
+  TRACE_EVENT_INSTANT_WITH_TIMESTAMP(
+      "startup", "Startup.BrowserProcessCreation", 0,
+      g_process_creation_ticks.Get().ToInternalValue());
+
+  TRACE_EVENT_INSTANT_WITH_TIMESTAMP(
+      "startup", "Startup.BrowserMainEntryPoint", 0,
+      g_main_entry_point_ticks.Get().ToInternalValue());
+}

[gab, 2015/11/12 14:41:38]

Also, FYI going forward, I think telemetry should care about more of the timings
in this file (which are mostly all more relevant than "main entry point" -- e.g.
first paint, etc.).

[gabadie, 2015/11/12 17:43:33]

Telemetry w'll use thoses values to diff to other instant events on its own side
for convenience, the reason why it is done this way.

+
 }  // namespace
 
 bool WasNonBrowserUIDisplayed() {
   return g_non_browser_ui_displayed;
 }
 
 void SetNonBrowserUIDisplayed() {
   g_non_browser_ui_displayed = true;
 }
 
@@ skipping 17 matching lines @@
 
 void RecordExeMainEntryPointTime(const base::Time& time) {
   const std::string exe_load_ticks =
       base::Int64ToString(StartupTimeToTimeTicks(time).ToInternalValue());
   scoped_ptr<base::Environment> env(base::Environment::Create());
   env->SetVar(kChromeMainTicksEnvVar, exe_load_ticks);
 }
 
 void RecordBrowserMainMessageLoopStart(const base::TimeTicks& ticks,
                                        bool is_first_run) {
+  AddStartupEventsForTelemetry();
   RecordHardFaultHistogram(is_first_run);
   RecordMainEntryTimeHistogram();
 
   const base::TimeTicks& process_creation_ticks =
       g_process_creation_ticks.Get();
   if (!is_first_run && !process_creation_ticks.is_null()) {
     UMA_HISTOGRAM_AND_TRACE_WITH_STARTUP_TEMPERATURE(
         UMA_HISTOGRAM_LONG_TIMES_100, "Startup.BrowserMessageLoopStartTime",
         process_creation_ticks, ticks);
   }
@@ skipping 153 matching lines @@
 
 base::TimeTicks MainEntryPointTicks() {
   return g_main_entry_point_ticks.Get();
 }
 
 StartupTemperature GetStartupTemperature() {
   return g_startup_temperature;
 }
 
 }  // namespace startup_metric_utils