Split PrefService into PrefService, PrefServiceSimple and PrefServiceSyncable.

chrome/browser/first_run/first_run.cc

Index: chrome/browser/first_run/first_run.cc
diff --git a/chrome/browser/first_run/first_run.cc b/chrome/browser/first_run/first_run.cc
index 8ce4f47c52c09ddc0783adae8c59f1bfcfb02a02..b95181bd17a09a7c98c826ed279ea15e824a1566 100644
--- a/chrome/browser/first_run/first_run.cc
+++ b/chrome/browser/first_run/first_run.cc
@@ -511,10 +511,10 @@ std::string GetPingDelayPrefName() {
                             installer::master_preferences::kDistroPingDelay);
 }
 
-void RegisterUserPrefs(PrefService* prefs) {
+void RegisterUserPrefs(PrefServiceSyncable* prefs) {
   prefs->RegisterIntegerPref(GetPingDelayPrefName().c_str(),
                              0,
-                             PrefService::UNSYNCABLE_PREF);
+                             PrefServiceSyncable::UNSYNCABLE_PREF);
 }
 
 bool RemoveSentinel() {
@@ -533,7 +533,7 @@ bool SetShowFirstRunBubblePref(bool show_bubble) {
 }
 
 bool SetShowWelcomePagePref() {
-  PrefService* local_state = g_browser_process->local_state();
+  PrefServiceSimple* local_state = g_browser_process->local_state();
   if (!local_state)
     return false;
   if (!local_state->FindPreference(prefs::kShouldShowWelcomePage)) {
@@ -544,7 +544,7 @@ bool SetShowWelcomePagePref() {
 }
 
 bool SetPersonalDataManagerFirstRunPref() {
-  PrefService* local_state = g_browser_process->local_state();
+  PrefServiceSimple* local_state = g_browser_process->local_state();
   if (!local_state)
     return false;
   if (!local_state->FindPreference(