mac: Add a profiler for startup time.

components/startup_metric_utils/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/startup_metric_utils.h"
 
 #include "base/containers/hash_tables.h"
 #include "base/environment.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
@@ skipping 211 matching lines @@
         kStartupTimeMin,
         kStartupTimeMax,
         kStartupTimeBuckets,
         base::Histogram::kUmaTargetedHistogramFlag);
     counter->AddTime(i->second);
   }
 
   g_startup_stats_collection_finished = true;
 }
 
+const base::Time* MainEntryPointTime() {
+  if (!g_main_entry_time_was_recorded)
+    return NULL;
+  return MainEntryPointTimeInternal();
+}
+
 ScopedSlowStartupUMA::~ScopedSlowStartupUMA() {
   if (g_startup_stats_collection_finished)
     return;
 
   base::AutoLock locker(*GetSubsystemStartupTimeHashLock());
   SubsystemStartupTimeHash* hash = GetSubsystemStartupTimeHash();
   // Only record the initial sample for a given histogram.
   if (hash->find(histogram_name_) !=  hash->end())
     return;
 
   (*hash)[histogram_name_] =
       base::TimeTicks::Now() - start_time_;
 }
 
 }  // namespace startup_metric_utils