Introduce PrefRegistrySyncable, simplifying PrefServiceSyncable.

chrome/browser/profiles/off_the_record_profile_impl.cc

Index: chrome/browser/profiles/off_the_record_profile_impl.cc
diff --git a/chrome/browser/profiles/off_the_record_profile_impl.cc b/chrome/browser/profiles/off_the_record_profile_impl.cc
index af37bd22a94f95daf048e165f2358bc5636d177b..0f1947264716369690c2548b279689be75105605 100644
--- a/chrome/browser/profiles/off_the_record_profile_impl.cc
+++ b/chrome/browser/profiles/off_the_record_profile_impl.cc
@@ -32,7 +32,7 @@
 #include "chrome/browser/plugins/chrome_plugin_service_filter.h"
 #include "chrome/browser/plugins/plugin_prefs.h"
 #include "chrome/browser/prefs/incognito_mode_prefs.h"
-#include "chrome/browser/prefs/pref_service.h"
+#include "chrome/browser/prefs/pref_service_syncable.h"
 #include "chrome/browser/profiles/profile_dependency_manager.h"
 #include "chrome/browser/themes/theme_service.h"
 #include "chrome/browser/ui/webui/extensions/extension_icon_source.h"
@@ -85,7 +85,7 @@ void NotifyOTRProfileDestroyedOnIOThread(void* original_profile,
 
 OffTheRecordProfileImpl::OffTheRecordProfileImpl(Profile* real_profile)
     : profile_(real_profile),
-      prefs_(real_profile->GetOffTheRecordPrefs()),
+      prefs_(PrefServiceSyncable::IncognitoFromProfile(real_profile)),

[Mattias Nissler (ping if slow), 2013/02/06 17:53:33]

Do we really need a PrefServiceSyncable typed pointer? Can we possibly declare
prefs_ to be of type PrefService?

[Jói, 2013/02/07 14:52:32]

I think we probably could, but we'd be casting it in a few more places and it'd
be less typesafe. Note that profile.h and related headers don't #include the
PrefServiceSyncable header, they just forward-declare the class so that they can
store a pointer to it, so changing the type wouldn't hide it any better than
it's hidden now...

[Mattias Nissler (ping if slow), 2013/02/08 11:26:56]

OK for now.

       ALLOW_THIS_IN_INITIALIZER_LIST(io_data_(this)),
       start_time_(Time::Now()) {
 }
@@ -238,11 +238,11 @@ policy::PolicyService* OffTheRecordProfileImpl::GetPolicyService() {
   return profile_->GetPolicyService();
 }
 
-PrefServiceSyncable* OffTheRecordProfileImpl::GetPrefs() {
+PrefService* OffTheRecordProfileImpl::GetPrefs() {
   return prefs_;
 }
 
-PrefServiceSyncable* OffTheRecordProfileImpl::GetOffTheRecordPrefs() {
+PrefService* OffTheRecordProfileImpl::GetOffTheRecordPrefs() {
   return prefs_;
 }
 
@@ -456,7 +456,7 @@ class GuestSessionProfile : public OffTheRecordProfileImpl {
 
   virtual void InitChromeOSPreferences() {
     chromeos_preferences_.reset(new chromeos::Preferences());
-    chromeos_preferences_->Init(GetPrefs());
+    chromeos_preferences_->Init(static_cast<PrefServiceSyncable*>(GetPrefs()));
   }
 
  private: