[Device Discovery] Make DialRegistry a Singleton

chrome/browser/media/router/discovery/dial/dial_registry_factory_unittest.cc

+// Copyright 2017 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 <memory>
+
+#include "base/memory/ptr_util.h"
+#include "chrome/browser/media/router/discovery/dial/dial_registry.h"
+#include "chrome/browser/media/router/discovery/dial/dial_registry_factory.h"
+#include "chrome/test/base/testing_profile.h"
+#include "content/public/browser/browser_context.h"
+#include "content/public/test/test_browser_thread_bundle.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace media_router {
+
+class DialRegistryFactoryTest : public testing::Test {
+ protected:
+  DialRegistryFactoryTest() {}
+  ~DialRegistryFactoryTest() override {}
+
+  Profile* profile() { return &profile_; }
+
+ private:
+  content::TestBrowserThreadBundle thread_bundle_;
+  TestingProfile profile_;
+};
+
+TEST_F(DialRegistryFactoryTest, CreateForRegularProfile) {
+  ASSERT_TRUE(DialRegistryFactory::GetForBrowserContext(profile()));
+}
+
+TEST_F(DialRegistryFactoryTest, CreateForIncognitoProfile) {
+  Profile* incognito_profile = profile()->GetOffTheRecordProfile();
+  ASSERT_TRUE(incognito_profile);
+
+  // Makes sure a DialRegistry can be created from an incognito Profile.
+  scoped_refptr<DialRegistry> dial_registry =
+      DialRegistryFactory::GetForBrowserContext(incognito_profile);
+  ASSERT_TRUE(dial_registry);
+
+  // A Profile and its incognito Profile share the same DialRegistry instance.
+  ASSERT_EQ(dial_registry,
+            DialRegistryFactory::GetForBrowserContext(profile()));
+}
+
+}  // namespace media_router