[Media Router] Ensure the same FeatureSwitch is used for lifetime of the

chrome/browser/media/router/media_router_feature.cc

 // Copyright 2015 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/media/router/media_router_feature.h"
 
 #include "build/build_config.h"
 #include "content/public/browser/browser_context.h"
 
 #if defined(ENABLE_EXTENSIONS)
-#include "chrome/browser/extensions/api/tab_capture/tab_capture_api.h"
-#include "extensions/browser/extension_registry.h"
-#include "extensions/common/extension_set.h"
 #include "extensions/common/feature_switch.h"
 #endif
 
 namespace media_router {
 
 bool MediaRouterEnabled(content::BrowserContext* context) {
 #if defined(ENABLE_MEDIA_ROUTER)
 #if defined(OS_ANDROID)
   return true;
 #elif defined(ENABLE_EXTENSIONS)
-  extensions::ExtensionRegistry* registry =
-      extensions::ExtensionRegistry::Get(context);
-  if (!registry) {
-    DLOG(ERROR) << "ExtensionRegistry is null. Assume no cast extension "
-                   "installed.";
-    return extensions::FeatureSwitch::media_router()->IsEnabled();
-  }
-
-  const extensions::ExtensionSet& extension_set =
-      registry->enabled_extensions();
-  if (extension_set.Contains(extensions::kStableChromecastExtensionId) ||
-      extension_set.Contains(extensions::kBetaChromecastExtensionId)) {
-    return extensions::FeatureSwitch::media_router_with_cast_extension()
-        ->IsEnabled();
-  }
-
   return extensions::FeatureSwitch::media_router()->IsEnabled();
 #else  // !defined(ENABLE_EXTENSIONS)
   return false;
 #endif  // defined(OS_ANDROID)
 #else   // !defined(ENABLE_MEDIA_ROUTER)
   return false;
 #endif  // defined(ENABLE_MEDIA_ROUTER)
 }
 
 }  // namespace media_router