Add ability to change default pref values, and use in BrowserInstantController.

chrome/browser/content_settings/content_settings_pref_provider_unittest.cc

Index: chrome/browser/content_settings/content_settings_pref_provider_unittest.cc
diff --git a/chrome/browser/content_settings/content_settings_pref_provider_unittest.cc b/chrome/browser/content_settings/content_settings_pref_provider_unittest.cc
index ffa7bca43f7d7377e2f5be0383a010abefd07e66..b4e0331bd3efbfa02fd16aa9e4ddab8d43785df8 100644
--- a/chrome/browser/content_settings/content_settings_pref_provider_unittest.cc
+++ b/chrome/browser/content_settings/content_settings_pref_provider_unittest.cc
@@ -139,13 +139,13 @@ TEST_F(PrefProviderTest, Incognito) {
   scoped_refptr<PrefRegistrySyncable> registry(new PrefRegistrySyncable);
   PrefServiceSyncable* regular_prefs = builder.CreateSyncable(registry);
 
-  chrome::RegisterUserPrefs(regular_prefs, registry);
+  chrome::RegisterUserPrefs(registry);
 
   builder.WithUserPrefs(otr_user_prefs);
   scoped_refptr<PrefRegistrySyncable> otr_registry(new PrefRegistrySyncable);
   PrefServiceSyncable* otr_prefs = builder.CreateSyncable(otr_registry);
 
-  chrome::RegisterUserPrefs(otr_prefs, otr_registry);
+  chrome::RegisterUserPrefs(otr_registry);
 
   TestingProfile::Builder profile_builder;
   profile_builder.SetPrefService(make_scoped_ptr(regular_prefs));