Pref service: Add initial support for pref registration.

services/preferences/pref_service_factory_unittest.cc

Index: services/preferences/pref_service_factory_unittest.cc
diff --git a/services/preferences/pref_service_factory_unittest.cc b/services/preferences/pref_service_factory_unittest.cc
index 462d0d34deb83482a467c4973c4fe078b7e69f69..de302dd5b9d43cb52c2a15fe6b01832b5dcdb824 100644
--- a/services/preferences/pref_service_factory_unittest.cc
+++ b/services/preferences/pref_service_factory_unittest.cc
@@ -163,8 +163,7 @@ class PrefServiceFactoryTest : public base::MessageLoop::DestructionObserver,
 TEST_F(PrefServiceFactoryTest, Basic) {
   auto pref_service = Create();
 
-  // TODO(tibell): Once we have a default store check the value prior to
-  // setting.
+  EXPECT_EQ(kInitialValue, pref_service->GetInteger(kKey));
   pref_service->SetInteger(kKey, kUpdatedValue);
   EXPECT_EQ(kUpdatedValue, pref_service->GetInteger(kKey));
 }
@@ -174,8 +173,8 @@ TEST_F(PrefServiceFactoryTest, MultipleClients) {
   auto pref_service = Create();
   auto pref_service2 = Create();
 
-  // TODO(tibell): Once we have a default store check the value prior to
-  // setting.
+  EXPECT_EQ(kInitialValue, pref_service->GetInteger(kKey));
+  EXPECT_EQ(kInitialValue, pref_service2->GetInteger(kKey));
   pref_service->SetInteger(kKey, kUpdatedValue);
   WaitForPrefChange(pref_service2.get(), kKey);
   EXPECT_EQ(kUpdatedValue, pref_service2->GetInteger(kKey));