Make extensions DSE persistent in browser prefs

components/sync_preferences/testing_pref_service_syncable.h

Index: components/sync_preferences/testing_pref_service_syncable.h
diff --git a/components/sync_preferences/testing_pref_service_syncable.h b/components/sync_preferences/testing_pref_service_syncable.h
index 521b80237c243467375d69b0aaaee28f7a8b458f..cf83573fcdf374ecaa3b05d7b943fae38f3f8ee6 100644
--- a/components/sync_preferences/testing_pref_service_syncable.h
+++ b/components/sync_preferences/testing_pref_service_syncable.h
@@ -22,6 +22,7 @@ class TestingPrefServiceSyncable
  public:
   TestingPrefServiceSyncable();
   TestingPrefServiceSyncable(TestingPrefStore* managed_prefs,
+                             TestingPrefStore* extension_prefs,

[vasilii, 2016/12/06 19:16:42]

I have mixed feelings about this. ExtensionPrefValueMap and ExtensionPrefs are
defined in extensions/. The component shouldn't depend on the extensions/
On the other hand, PrefValueStore already knows the extensions perfectly. I'll
defer to the owners of the directory.

[gab, 2016/12/06 19:35:04]

That's a good point. FWIW, a dependency on policies (i.e. managed_prefs and
recommended_prefs) is also wrong here.

This was moved from chrome/ where it was okay to speak on those terms. Here we'd
ideally be using a generic naming for the same mappings.

[Alexander Yashkin, 2016/12/09 08:19:52]

Whats wrong with it? 
Preference class declared in src/components/prefs/pref_service.h has IsManaged,
IsExtensionControlled methods 
so there should be a convenient way to set/get such prefs in unittests without
creating complex reallife ExtensionPrefValueMap and ExtensionPrefs objects. 
I thought that was the idea behind TestingPrefServiceSyncable and thats why its
so widely used in tests.

                              TestingPrefStore* user_prefs,
                              TestingPrefStore* recommended_prefs,
                              user_prefs::PrefRegistrySyncable* pref_registry,
@@ -45,6 +46,7 @@ template <>
 TestingPrefServiceBase<sync_preferences::PrefServiceSyncable,
                        user_prefs::PrefRegistrySyncable>::
     TestingPrefServiceBase(TestingPrefStore* managed_prefs,
+                           TestingPrefStore* extension_prefs,
                            TestingPrefStore* user_prefs,
                            TestingPrefStore* recommended_prefs,
                            user_prefs::PrefRegistrySyncable* pref_registry,