Replace direct access to kGoogleServicesUsername with calls to SigninManager.

chrome/browser/sync/profile_sync_service_mock.cc

Index: chrome/browser/sync/profile_sync_service_mock.cc
diff --git a/chrome/browser/sync/profile_sync_service_mock.cc b/chrome/browser/sync/profile_sync_service_mock.cc
index f2fc5c1d33dc09a5e0bb31ab0c5b10baba6e3815..1bdcc4dd1fb10e569443ba6323c62b8f129da520 100644
--- a/chrome/browser/sync/profile_sync_service_mock.cc
+++ b/chrome/browser/sync/profile_sync_service_mock.cc
@@ -46,7 +46,8 @@ ProfileSyncServiceMock::~ProfileSyncServiceMock() {
 // static
 TestingProfile* ProfileSyncServiceMock::MakeSignedInTestingProfile() {
   TestingProfile* profile = new TestingProfile();
-  profile->GetPrefs()->SetString(prefs::kGoogleServicesUsername, "foo");
+  SigninManagerFactory::GetForProfile(profile)->
+      SetAuthenticatedUsername("foo");
   return profile;
 }