Delete some unused code found by -Wunused-function

chrome/browser/extensions/settings/settings_sync_unittest.cc

Index: chrome/browser/extensions/settings/settings_sync_unittest.cc
diff --git a/chrome/browser/extensions/settings/settings_sync_unittest.cc b/chrome/browser/extensions/settings/settings_sync_unittest.cc
index 26ce96a19e8c59c8e9fc8389d1d140f886c567f7..5ac27d95876b736ceace6aaeaa1873b92de047b7 100644
--- a/chrome/browser/extensions/settings/settings_sync_unittest.cc
+++ b/chrome/browser/extensions/settings/settings_sync_unittest.cc
@@ -194,12 +194,6 @@ class TestingValueStoreFactory : public SettingsStorageFactory {
   std::map<std::string, TestingValueStore*> created_;
 };
 
-void AssignSettingsService(syncer::SyncableService** dst,
-                           const SettingsFrontend* frontend,
-                           syncer::ModelType type) {
-  *dst = frontend->GetBackendForSync(type);
-}
-
 }  // namespace
 
 class ExtensionSettingsSyncTest : public testing::Test {