cros: Enable WebUILoginView reuse.

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

+// 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.
+
+#include "chrome/browser/chromeos/login/ui/shared_web_view_factory.h"
+
+#include "chrome/browser/chromeos/login/ui/shared_web_view.h"
+#include "chrome/browser/chromeos/profiles/profile_helper.h"
+#include "chrome/browser/profiles/incognito_helpers.h"
+#include "chrome/browser/profiles/profile.h"
+#include "components/keyed_service/content/browser_context_dependency_manager.h"
+
+namespace chromeos {
+
+// static
+SharedWebView* SharedWebViewFactory::GetForProfile(Profile* profile) {
+  auto result = static_cast<SharedWebView*>(
+      GetInstance()->GetServiceForBrowserContext(profile, true));
+  return result;
+}
+
+// static
+SharedWebViewFactory* SharedWebViewFactory::GetInstance() {
+  return base::Singleton<SharedWebViewFactory>::get();
+}
+
+SharedWebViewFactory::SharedWebViewFactory()
+    : BrowserContextKeyedServiceFactory(
+          "SharedWebViewFactory",
+          BrowserContextDependencyManager::GetInstance()) {}
+
+SharedWebViewFactory::~SharedWebViewFactory() {}
+
+content::BrowserContext* SharedWebViewFactory::GetBrowserContextToUse(
+    content::BrowserContext* context) const {
+  // Make sure that only the SigninProfile is using a shared webview.
+  if (Profile::FromBrowserContext(context) != ProfileHelper::GetSigninProfile())
+    return nullptr;
+
+  return context;
+}
+
+KeyedService* SharedWebViewFactory::BuildServiceInstanceFor(
+    content::BrowserContext* context) const {
+  return new SharedWebView(Profile::FromBrowserContext(context));
+}
+
+}  // namespace chromeos