Remove PrefServiceSimple, replacing it with PrefService and PrefRegistrySimple.

chrome/browser/chromeos/power/session_length_limiter.cc

Index: chrome/browser/chromeos/power/session_length_limiter.cc
diff --git a/chrome/browser/chromeos/power/session_length_limiter.cc b/chrome/browser/chromeos/power/session_length_limiter.cc
index 8a716bc9b34a01cbd2a2b919c8336521a8299881..c33af0baa24cf6715792812ebc25df0d5195f795 100644
--- a/chrome/browser/chromeos/power/session_length_limiter.cc
+++ b/chrome/browser/chromeos/power/session_length_limiter.cc
@@ -65,7 +65,7 @@ SessionLengthLimiter::Delegate::~Delegate() {
 }
 
 // static
-void SessionLengthLimiter::RegisterPrefs(PrefServiceSimple* local_state) {
+void SessionLengthLimiter::RegisterPrefs(PrefRegistrarSimple* local_state) {
   local_state->RegisterInt64Pref(prefs::kSessionStartTime, 0);
   local_state->RegisterIntegerPref(prefs::kSessionLengthLimit, 0);
 }