Add a new GetInstance() method for remaining files with singleton classes under chrome/browser.

chrome/browser/chromeos/audio_handler.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/browser/chromeos/audio_handler.h"
 
 #include <math.h>
 
 #include "base/logging.h"
 #include "chrome/browser/chromeos/pulse_audio_mixer.h"
@@ skipping 150 matching lines @@
   return 100.0 * pow((volume_db - kMinVolumeDb) /
       (kMaxVolumeDb - kMinVolumeDb), 1/kVolumeBias);
 }
 
 // static
 double AudioHandler::PercentToVolumeDb(double volume_percent) {
   return pow(volume_percent / 100.0, kVolumeBias) *
       (kMaxVolumeDb - kMinVolumeDb) + kMinVolumeDb;
 }
 
+// static
+AudioHandler* AudioHandler::instance() {
+  return Singleton<AudioHandler>::get();
+}
+
 }  // namespace chromeos