Re-add support for Chromecast

Fixes brave/brave-browser#209

Revert "Merge pull request #2119 from brave/revert_enabling_chromecast"
This reverts commit 29ea1df, reversing
changes made to c08710a.

Author: bsclifton

chromium_src/extensions/common/feature_switch.cc

@@ -0,0 +1,8 @@
+/* Copyright (c) 2019 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#define GOOGLE_CHROME_BUILD
+#include "../../../../extensions/common/feature_switch.cc"  // NOLINT
+#undef GOOGLE_CHROME_BUILD

chromium_src/extensions/common/feature_switch_unittest.cc

@@ -0,0 +1,14 @@
+/* Copyright (c) 2019 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "extensions/common/feature_switch.h"
+
+#include "base/command_line.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+TEST(BraveFeatureSwitchTest, LoadMediaRouterComponentExtensionFlagTest) {
+  EXPECT_TRUE(extensions::FeatureSwitch::load_media_router_component_extension()
+      ->IsEnabled());
+}

test/BUILD.gn

@@ -76,6 +76,7 @@ test("brave_unit_tests") {
     "//brave/chromium_src/components/search_engines/brave_template_url_service_util_unittest.cc",
     "//brave/chromium_src/components/translate/core/browser/translate_manager_unittest.cc",
     "//brave/chromium_src/components/version_info/brave_version_info_unittest.cc",
+    "//brave/chromium_src/extensions/common/feature_switch_unittest.cc",
     "//brave/chromium_src/net/cookies/brave_canonical_cookie_unittest.cc",
     "//brave/common/brave_content_client_unittest.cc",
     "//brave/common/importer/brave_mock_importer_bridge.cc",