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

chrome/browser/chromeos/login/quick_unlock/quick_unlock_storage_unittest.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/login/quick_unlock/quick_unlock_storage.h"
 
 #include "chrome/browser/chromeos/login/quick_unlock/quick_unlock_factory.h"
 #include "chrome/browser/chromeos/login/quick_unlock/quick_unlock_utils.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/test/base/testing_profile.h"
@@ skipping 16 matching lines @@
   return quick_unlock::PasswordConfirmationFrequencyToTimeDelta(
       static_cast<quick_unlock::PasswordConfirmationFrequency>(frequency));
 }
 
 class QuickUnlockStorageUnitTest : public testing::Test {
  protected:
   QuickUnlockStorageUnitTest() : profile_(new TestingProfile()) {}
   ~QuickUnlockStorageUnitTest() override {}
 
   // testing::Test:
-  void SetUp() override { quick_unlock::EnableForTesting(); }
+  void SetUp() override {
+    quick_unlock::EnableForTesting(quick_unlock::PinStorageProvider::Prefs);
+  }
 
   content::TestBrowserThreadBundle thread_bundle_;
   std::unique_ptr<TestingProfile> profile_;
 
   DISALLOW_COPY_AND_ASSIGN(QuickUnlockStorageUnitTest);
 };
 
 }  // namespace
 
 // Provides test-only QuickUnlockStorage APIs.
@@ skipping 95 matching lines @@
   expiration_time = GetExpirationTime(pref_service);
   EXPECT_TRUE(quick_unlock_storage->HasStrongAuth());
   test_api.ReduceRemainingStrongAuthTimeBy(expiration_time);
   EXPECT_FALSE(quick_unlock_storage->HasStrongAuth());
   SetConfirmationFrequency(
       pref_service, quick_unlock::PasswordConfirmationFrequency::TWELVE_HOURS);
   EXPECT_TRUE(quick_unlock_storage->HasStrongAuth());
 }
 
 }  // namespace chromeos