Remove signin_error_notifier_ash unittest dependencies on SigninManager

This CL is part of the long-term goal of eliminating SigninManager as a
public API for Chromium's identity code, replaced by IdentityManager.

signin_error_notifer_ash_unittest builds a fake signin manager.
This is not necessary: tests succeed without that.
So removed creation of unused fake signin manager from tests.

Bug: 797899
Change-Id: I7bcfca18f2c94192e629385a7c481957387e7fec
Reviewed-on: https://chromium-review.googlesource.com/1158685Reviewed-by: David Roger <droger@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Commit-Queue: Jean-Denis Muys <jdmuys@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581190}

chrome/browser/signin/signin_error_notifier_ash_unittest.cc

@@ -14,16 +14,13 @@
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chromeos/login/users/mock_user_manager.h"
 #include "chrome/browser/notifications/notification_display_service_tester.h"
-#include "chrome/browser/signin/fake_signin_manager_builder.h"
 #include "chrome/browser/signin/signin_error_controller_factory.h"
 #include "chrome/browser/signin/signin_error_notifier_factory_ash.h"
-#include "chrome/browser/signin/signin_manager_factory.h"
 #include "chrome/test/base/browser_with_test_window_test.h"
 #include "chrome/test/base/testing_profile.h"
 #include "chrome/test/base/testing_profile_manager.h"
 #include "components/signin/core/browser/fake_auth_status_provider.h"
 #include "components/signin/core/browser/signin_error_controller.h"
-#include "components/signin/core/browser/signin_manager.h"
 #include "components/user_manager/scoped_user_manager.h"
 #include "content/public/test/test_browser_thread_bundle.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -54,10 +51,6 @@ class SigninErrorNotifierTest : public BrowserWithTestWindowTest {
         std::make_unique<NotificationDisplayServiceTester>(profile());
   }
 
-  TestingProfile::TestingFactories GetTestingFactories() override {
-    return {{SigninManagerFactory::GetInstance(), BuildFakeSigninManagerBase}};
-  }
-
  protected:
   SigninErrorController* error_controller_;
   std::unique_ptr<NotificationDisplayServiceTester> display_service_;