Use lock-free lazy initialization for static histogram references

chrome/browser/chromeos/cros/cros_library_loader.cc

-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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/chromeos/cros/cros_library_loader.h"
 
 #include <dlfcn.h>
 
 #include "base/file_path.h"
 #include "base/metrics/histogram.h"
 #include "base/logging.h"
 #include "base/path_service.h"
 #include "chrome/common/chrome_paths.h"
 #include "third_party/cros/chromeos_cros_api.h"
 
 namespace chromeos {
 
 namespace {
 
 void addLibcrosTimeHistogram(const char* name, const base::TimeDelta& delta) {
   static const base::TimeDelta min_time = base::TimeDelta::FromMilliseconds(1);
   static const base::TimeDelta max_time = base::TimeDelta::FromSeconds(1);
   const size_t bucket_count(10);
   DCHECK(name);
-  scoped_refptr<base::Histogram> counter = base::Histogram::FactoryTimeGet(
+  base::Histogram* counter = base::Histogram::FactoryTimeGet(
       std::string(name),
       min_time,
       max_time,
       bucket_count,
       base::Histogram::kNoFlags);
-  if (counter.get()) {
-    counter->AddTime(delta);
-    VLOG(1) << "Cros Time: " << name << ": " << delta.InMilliseconds() << "ms.";
-  }
+  counter->AddTime(delta);
+  VLOG(1) << "Cros Time: " << name << ": " << delta.InMilliseconds() << "ms.";
 }
 
 }  // namespace
 
 bool CrosLibraryLoader::Load(std::string* load_error_string) {
   bool loaded = false;
   FilePath path;
   if (PathService::Get(chrome::FILE_CHROMEOS_API, &path)) {
     loaded = LoadLibcros(path.value().c_str(), *load_error_string);
     if (loaded)
       SetLibcrosTimeHistogramFunction(addLibcrosTimeHistogram);
   }
 
   if (!loaded) {
     LOG(ERROR) << "Problem loading chromeos shared object: "
                << *load_error_string;
   }
   return loaded;
 }
 
 }   // namespace chromeos