cros: Only preload the lock screen; do not reuse it.

chrome/browser/chromeos/login/ui/preloaded_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_PRELOADED_WEB_VIEW_FACTORY_H_
+#define CHROME_BROWSER_CHROMEOS_LOGIN_UI_PRELOADED_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 PreloadedWebView;
+
+// Fetches a PreloadedWebView instance for the signin profile.
+class PreloadedWebViewFactory : public BrowserContextKeyedServiceFactory {
+ public:
+  static PreloadedWebView* GetForProfile(Profile* profile);
+
+  static PreloadedWebViewFactory* GetInstance();
+
+ private:
+  friend struct base::DefaultSingletonTraits<PreloadedWebViewFactory>;
+
+  PreloadedWebViewFactory();
+  ~PreloadedWebViewFactory() override;
+
+  // BrowserContextKeyedServiceFactory:
+  content::BrowserContext* GetBrowserContextToUse(
+      content::BrowserContext* context) const override;
+  KeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* profile) const override;
+
+  DISALLOW_COPY_AND_ASSIGN(PreloadedWebViewFactory);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_LOGIN_UI_PRELOADED_WEB_VIEW_FACTORY_H_