Split PrefService into PrefService, PrefServiceSimple and PrefServiceSyncable.

chrome/browser/io_thread.cc

Index: chrome/browser/io_thread.cc
diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index 65a555fa7c49894c4ba5440d7845fb997bd75af0..d53faac04ade3f672e3889d23e159483ca1cf350 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -357,7 +357,7 @@ IOThread::Globals::~Globals() {}
 // |local_state| is passed in explicitly in order to (1) reduce implicit
 // dependencies and (2) make IOThread more flexible for testing.
 IOThread::IOThread(
-    PrefService* local_state,
+    PrefServiceSimple* local_state,
     policy::PolicyService* policy_service,
     ChromeNetLog* net_log,
     extensions::EventRouterForwarder* extension_event_router_forwarder)
@@ -718,7 +718,7 @@ void IOThread::EnableSpdy(const std::string& mode) {
 }
 
 // static
-void IOThread::RegisterPrefs(PrefService* local_state) {
+void IOThread::RegisterPrefs(PrefServiceSimple* local_state) {
   local_state->RegisterStringPref(prefs::kAuthSchemes,
                                   "basic,digest,ntlm,negotiate,"
                                   "spdyproxy");