cros: Enable WebUILoginView reuse.

chrome/browser/chromeos/login/ui/shared_web_view_factory.h

+// Copyright 2016 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_CHROMEOS_LOGIN_UI_SHARED_WEB_VIEW_FACTORY_H_
+#define CHROME_BROWSER_CHROMEOS_LOGIN_UI_SHARED_WEB_VIEW_FACTORY_H_
+
+#include "base/macros.h"
+#include "base/memory/singleton.h"
+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+
+class Profile;
+
+namespace chromeos {
+
+class SharedWebView;
+
+// Fetches a SharedWebView instance for the signin profile.
+class SharedWebViewFactory : public BrowserContextKeyedServiceFactory {
+ public:
+  static SharedWebView* GetForProfile(Profile* profile);
+
+  static SharedWebViewFactory* GetInstance();
+
+ private:
+  friend struct base::DefaultSingletonTraits<SharedWebViewFactory>;
+
+  SharedWebViewFactory();
+  ~SharedWebViewFactory() override;
+
+  // BrowserContextKeyedServiceFactory:
+  content::BrowserContext* GetBrowserContextToUse(
+      content::BrowserContext* context) const override;
+  KeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* profile) const override;
+
+  DISALLOW_COPY_AND_ASSIGN(SharedWebViewFactory);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_LOGIN_UI_SHARED_WEB_VIEW_FACTORY_H_