Revert of Delete dead signin code (SigninGlobalError)

chrome/browser/signin/signin_global_error_factory.h

Index: chrome/browser/signin/signin_global_error_factory.h
diff --git a/chrome/browser/signin/signin_global_error_factory.h b/chrome/browser/signin/signin_global_error_factory.h
new file mode 100644
index 0000000000000000000000000000000000000000..36bb94c57133a32df4a00c321c11e0bf9e94872c
--- /dev/null
+++ b/chrome/browser/signin/signin_global_error_factory.h
@@ -0,0 +1,39 @@
+// Copyright 2014 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.
+
+#ifndef CHROME_BROWSER_SIGNIN_SIGNIN_GLOBAL_ERROR_FACTORY_H_
+#define CHROME_BROWSER_SIGNIN_SIGNIN_GLOBAL_ERROR_FACTORY_H_
+
+#include "base/memory/singleton.h"
+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+
+class SigninGlobalError;
+class Profile;
+
+// Singleton that owns all SigninGlobalErrors and associates them with
+// Profiles. Listens for the Profile's destruction notification and cleans up
+// the associated SigninGlobalError.
+class SigninGlobalErrorFactory : public BrowserContextKeyedServiceFactory {
+ public:
+  // Returns the instance of SigninGlobalError associated with this
+  // profile, creating one if none exists. In Ash, this will return NULL.
+  static SigninGlobalError* GetForProfile(Profile* profile);
+
+  // Returns an instance of the SigninGlobalErrorFactory singleton.
+  static SigninGlobalErrorFactory* GetInstance();
+
+ private:
+  friend struct DefaultSingletonTraits<SigninGlobalErrorFactory>;
+
+  SigninGlobalErrorFactory();
+  ~SigninGlobalErrorFactory() override;
+
+  // BrowserContextKeyedServiceFactory:
+  KeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* profile) const override;
+
+  DISALLOW_COPY_AND_ASSIGN(SigninGlobalErrorFactory);
+};
+
+#endif  // CHROME_BROWSER_SIGNIN_SIGNIN_GLOBAL_ERROR_FACTORY_H_