Remove dependency of PrefSyncableService on PrefsTabHelper.

chrome/browser/extensions/test_extension_prefs.cc

Index: chrome/browser/extensions/test_extension_prefs.cc
diff --git a/chrome/browser/extensions/test_extension_prefs.cc b/chrome/browser/extensions/test_extension_prefs.cc
index b91899b0dd137ca1ad216b43376bc5a2585ecd0a..7784408334b87199d74eb2cfc73845262d8c4d45 100644
--- a/chrome/browser/extensions/test_extension_prefs.cc
+++ b/chrome/browser/extensions/test_extension_prefs.cc
@@ -20,6 +20,7 @@
 #include "chrome/browser/extensions/test_extension_system.h"
 #include "chrome/browser/prefs/pref_service_mock_factory.h"
 #include "chrome/browser/prefs/pref_service_syncable.h"
+#include "chrome/browser/prefs/pref_service_syncable_util.h"
 #include "chrome/common/chrome_constants.h"
 #include "components/crx_file/id_util.h"
 #include "components/pref_registry/pref_registry_syncable.h"
@@ -197,7 +198,8 @@ void TestExtensionPrefs::AddExtension(Extension* extension) {
 }
 
 PrefService* TestExtensionPrefs::CreateIncognitoPrefService() const {
-  return pref_service_->CreateIncognitoPrefService(
+  return CreateIncognitoPrefServiceSyncable(
+      pref_service_.get(),
       new ExtensionPrefStore(extension_pref_value_map_.get(), true));
 }