Remove Chromecast extension support from cast system tray menu.

chrome/browser/ui/ash/system_tray_delegate_chromeos.cc

Index: chrome/browser/ui/ash/system_tray_delegate_chromeos.cc
diff --git a/chrome/browser/ui/ash/system_tray_delegate_chromeos.cc b/chrome/browser/ui/ash/system_tray_delegate_chromeos.cc
index 19a2ac5ae1feddd086dcf90113ae29747897078b..c471d5b569758f605f333e25698b5e2984418300 100644
--- a/chrome/browser/ui/ash/system_tray_delegate_chromeos.cc
+++ b/chrome/browser/ui/ash/system_tray_delegate_chromeos.cc
@@ -64,7 +64,6 @@
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/supervised_user/supervised_user_service.h"
 #include "chrome/browser/supervised_user/supervised_user_service_factory.h"
-#include "chrome/browser/ui/ash/cast_config_delegate_chromeos.h"
 #include "chrome/browser/ui/ash/cast_config_delegate_media_router.h"
 #include "chrome/browser/ui/ash/multi_user/multi_user_util.h"
 #include "chrome/browser/ui/ash/networking_config_delegate_chromeos.h"
@@ -139,12 +138,6 @@ void BluetoothDeviceConnectError(
     device::BluetoothDevice::ConnectErrorCode error_code) {
 }
 
-std::unique_ptr<ash::CastConfigDelegate> CreateCastConfigDelegate() {
-  if (CastConfigDelegateMediaRouter::IsEnabled())
-    return base::MakeUnique<CastConfigDelegateMediaRouter>();
-  return base::MakeUnique<CastConfigDelegateChromeos>();
-}
-
 void ShowSettingsSubPageForActiveUser(const std::string& sub_page) {
   chrome::ShowSettingsSubPageForProfile(
       ProfileManager::GetActiveUserProfile(), sub_page);
@@ -165,7 +158,7 @@ SystemTrayDelegateChromeOS::SystemTrayDelegateChromeOS()
       have_session_length_limit_(false),
       should_run_bluetooth_discovery_(false),
       session_started_(false),
-      cast_config_delegate_(nullptr),
+      cast_config_delegate_(base::MakeUnique<CastConfigDelegateMediaRouter>()),
       networking_config_delegate_(new NetworkingConfigDelegateChromeos()),
       vpn_delegate_(new VPNDelegateChromeOS),
       weak_ptr_factory_(this) {
@@ -573,8 +566,6 @@ bool SystemTrayDelegateChromeOS::GetBluetoothDiscovering() {
 }
 
 ash::CastConfigDelegate* SystemTrayDelegateChromeOS::GetCastConfigDelegate() {
-  if (!cast_config_delegate_)
-    cast_config_delegate_ = CreateCastConfigDelegate();
   return cast_config_delegate_.get();
 }