Make members of Singleton<T> private and only visible to the singleton type.

chrome/common/time_format.cc

 // Copyright (c) 2010 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/common/time_format.h"
 
 #include <vector>
 
 #include "app/l10n_util.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/scoped_ptr.h"
-#include "base/singleton.h"
 #include "base/stl_util-inl.h"
 #include "base/string16.h"
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "grit/generated_resources.h"
 #include "unicode/datefmt.h"
 #include "unicode/locid.h"
 #include "unicode/plurfmt.h"
 #include "unicode/plurrule.h"
 #include "unicode/smpdtfmt.h"
@@ skipping 138 matching lines @@
       BuildFormats(FORMAT_ELAPSED, &time_elapsed_formatter_);
     }
     ~TimeFormatter() {
       STLDeleteContainerPointers(short_formatter_.begin(),
                                  short_formatter_.end());
       STLDeleteContainerPointers(time_left_formatter_.begin(),
                                  time_left_formatter_.end());
       STLDeleteContainerPointers(time_elapsed_formatter_.begin(),
                                  time_elapsed_formatter_.end());
     }
-    friend class Singleton<TimeFormatter>;
-    friend struct DefaultSingletonTraits<TimeFormatter>;
+    friend struct base::DefaultLazyInstanceTraits<TimeFormatter>;
 
     std::vector<icu::PluralFormat*> short_formatter_;
     std::vector<icu::PluralFormat*> time_left_formatter_;
     std::vector<icu::PluralFormat*> time_elapsed_formatter_;
     static void BuildFormats(FormatType format_type,
                              std::vector<icu::PluralFormat*>* time_formats);
     static icu::PluralFormat* createFallbackFormat(
         const icu::PluralRules& rules, int index, FormatType format_type);
 
     DISALLOW_COPY_AND_ASSIGN(TimeFormatter);
 };
 
+static base::LazyInstance<TimeFormatter> g_time_formatter(
+    base::LINKER_INITIALIZED);
+
 void TimeFormatter::BuildFormats(
     FormatType format_type, std::vector<icu::PluralFormat*>* time_formats) {
   static const icu::UnicodeString kKeywords[] = {
     UNICODE_STRING_SIMPLE("other"), UNICODE_STRING_SIMPLE("one"),
     UNICODE_STRING_SIMPLE("zero"), UNICODE_STRING_SIMPLE("two"),
     UNICODE_STRING_SIMPLE("few"), UNICODE_STRING_SIMPLE("many")
   };
   UErrorCode err = U_ZERO_ERROR;
   scoped_ptr<icu::PluralRules> rules(
       icu::PluralRules::forLocale(icu::Locale::getDefault(), err));
@@ skipping 51 matching lines @@
   if (rules.isKeyword(UNICODE_STRING_SIMPLE("one"))) {
     pattern += UNICODE_STRING_SIMPLE("one{# ") + kUnits[index][0] + suffix;
   }
   pattern += UNICODE_STRING_SIMPLE(" other{# ") + kUnits[index][1] + suffix;
   UErrorCode err = U_ZERO_ERROR;
   icu::PluralFormat* format = new icu::PluralFormat(rules, pattern, err);
   DCHECK(U_SUCCESS(err));
   return format;
 }
 
-Singleton<TimeFormatter> time_formatter;
-
 static string16 FormatTimeImpl(const TimeDelta& delta, FormatType format_type) {
   if (delta.ToInternalValue() < 0) {
     NOTREACHED() << "Negative duration";
     return string16();
   }
 
   int number;
 
   const std::vector<icu::PluralFormat*>& formatters =
-    time_formatter->formatter(format_type);
+    g_time_formatter.Get().formatter(format_type);
 
   UErrorCode error = U_ZERO_ERROR;
   icu::UnicodeString time_string;
   // Less than a minute gets "X seconds left"
   if (delta.ToInternalValue() < Time::kMicrosecondsPerMinute) {
     number = static_cast<int>(delta.ToInternalValue() /
                               Time::kMicrosecondsPerSecond);
     time_string = formatters[0]->format(number, error);
 
   // Less than 1 hour gets "X minutes left".
@@ skipping 50 matching lines @@
 
   // Filter out "today" and "yesterday"
   if (time >= midnight_today)
     return l10n_util::GetStringUTF16(IDS_PAST_TIME_TODAY);
   else if (time >= midnight_today -
                    TimeDelta::FromMicroseconds(Time::kMicrosecondsPerDay))
     return l10n_util::GetStringUTF16(IDS_PAST_TIME_YESTERDAY);
 
   return string16();
 }