Remove PrefService::ScheduleSavePersistentPrefs and SavePersistentPrefs.

chrome/browser/chromeos/audio_mixer_alsa.cc

Index: chrome/browser/chromeos/audio_mixer_alsa.cc
diff --git a/chrome/browser/chromeos/audio_mixer_alsa.cc b/chrome/browser/chromeos/audio_mixer_alsa.cc
index 7898d16bed32a80af9d7878ef3cb03a7ea8587bb..a38271cceb566b9279124d6f1ab3e69a5c61edf4 100644
--- a/chrome/browser/chromeos/audio_mixer_alsa.cc
+++ b/chrome/browser/chromeos/audio_mixer_alsa.cc
@@ -138,7 +138,6 @@ void AudioMixerAlsa::SetVolumeDb(double volume_db) {
   }
 
   prefs_->SetDouble(prefs::kAudioVolume, volume_db);
-  prefs_->ScheduleSavePersistentPrefs();
 
   base::AutoLock lock(lock_);
   volume_db_ = volume_db;
@@ -155,7 +154,6 @@ bool AudioMixerAlsa::IsMuted() {
 void AudioMixerAlsa::SetMuted(bool muted) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   prefs_->SetInteger(prefs::kAudioMute, muted ? kPrefMuteOn : kPrefMuteOff);
-  prefs_->ScheduleSavePersistentPrefs();
   base::AutoLock lock(lock_);
   is_muted_ = muted;
   if (!apply_is_pending_)