mac: Add a profiler for startup time.

chrome/browser/mac/mac_startup_profiler.cc

+// 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.
+
+#include "chrome/browser/mac/mac_startup_profiler.h"
+
+#include "base/logging.h"
+#include "base/metrics/histogram.h"
+#include "components/startup_metric_utils/startup_metric_utils.h"
+
+// static
+MacStartupProfiler* MacStartupProfiler::GetInstance() {
+  return Singleton<MacStartupProfiler>::get();
+}
+
+MacStartupProfiler::MacStartupProfiler() : recorded_metrics_(false) {
+}
+
+MacStartupProfiler::~MacStartupProfiler() {
+}
+
+void MacStartupProfiler::Profile(Location location) {
+  profiled_times_[location] = base::Time::Now();
+}
+
+void MacStartupProfiler::RecordMetrics() {
+  const base::Time* launch_time = startup_metric_utils::MainEntryPointTime();

[jeremy, 2014/07/17 20:58:02]

nit: launch_time -> main_entry_time or somesuch

[erikchen, 2014/07/17 21:05:03]

I used your suggestion of main_entry_time.

+  DCHECK(launch_time);
+  DCHECK(!recorded_metrics_);
+
+  recorded_metrics_ = true;
+
+  for (std::map<Location, base::Time>::const_iterator it =
+           profiled_times_.begin();
+       it != profiled_times_.end();
+       ++it) {
+    const base::Time& location_time = it->second;
+    base::TimeDelta delta = location_time - *launch_time;
+    RecordHistogram(it->first, delta);
+  }
+}
+
+const std::string MacStartupProfiler::HistogramName(Location location) {
+  std::string prefix("Startup.OSX.");
+  switch (location) {
+    case PRE_MAIN_MESSAGE_LOOP_START:
+      return prefix + "PreMainMessageLoopStart";
+    case AWAKE_FROM_NIB:
+      return prefix + "AwakeFromNib";
+    case POST_MAIN_MESSAGE_LOOP_START:
+      return prefix + "PostMainMessageLoopStart";
+    case PRE_PROFILE_INIT:
+      return prefix + "PreProfileInit";
+    case POST_PROFILE_INIT:
+      return prefix + "PostProfileInit";
+    case WILL_FINISH_LAUNCHING:
+      return prefix + "WillFinishLaunching";
+    case DID_FINISH_LAUNCHING:
+      return prefix + "DockIconWillFinishBouncing";
+  }
+}
+
+void MacStartupProfiler::RecordHistogram(Location location,
+                                         const base::TimeDelta& delta) {
+  const std::string name(HistogramName(location));
+  base::TimeDelta min = base::TimeDelta::FromMilliseconds(10);
+  base::TimeDelta max = base::TimeDelta::FromMinutes(1);
+  int bucket_count = 100;
+
+  // No need to cache the histogram pointers, since each invocation of this
+  // method will be the first and only usage of a histogram with that given
+  // name.
+  base::HistogramBase* histogram = base::Histogram::FactoryTimeGet(
+      name,
+      min,
+      max,
+      bucket_count,
+      base::HistogramBase::kUmaTargetedHistogramFlag);
+  histogram->AddTime(delta);
+}