cros: Add PinStorageProvider enum which describes pin backend in use.

chrome/browser/chromeos/extensions/quick_unlock_private/quick_unlock_private_api_unittest.cc

Index: chrome/browser/chromeos/extensions/quick_unlock_private/quick_unlock_private_api_unittest.cc
diff --git a/chrome/browser/chromeos/extensions/quick_unlock_private/quick_unlock_private_api_unittest.cc b/chrome/browser/chromeos/extensions/quick_unlock_private/quick_unlock_private_api_unittest.cc
index a249299a36d1757967f5e55024ab0d4267c657ab..13cbf2d989828ed76abc232bf2888e19a5e651d5 100644
--- a/chrome/browser/chromeos/extensions/quick_unlock_private/quick_unlock_private_api_unittest.cc
+++ b/chrome/browser/chromeos/extensions/quick_unlock_private/quick_unlock_private_api_unittest.cc
@@ -76,7 +76,7 @@ class QuickUnlockPrivateUnitTest : public ExtensionApiUnittest {
   void SetUp() override {
     ExtensionApiUnittest::SetUp();
 
-    quick_unlock::EnableForTesting();
+    quick_unlock::EnableForTesting(quick_unlock::PinStorageType::kPrefs);
 
     // Setup a primary user.
     auto test_account = AccountId::FromUserEmail(kTestUserEmail);