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 5ac89b26a8f9e67b76d9cc729bf5c4503e3ffbe2..5438980139c7ecd29b325411769196004bfb76ef 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 OnAcceptMultiprofilesIntro(bool no_show_again) {
   PrefService* prefs = ProfileManager::GetActiveUserProfile()->GetPrefs();
   prefs->SetBoolean(prefs::kMultiProfileNeverShowIntro, no_show_again);
@@ -160,7 +153,7 @@ 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) {
@@ -566,8 +559,6 @@ bool SystemTrayDelegateChromeOS::GetBluetoothDiscovering() {
 }
 
 ash::CastConfigDelegate* SystemTrayDelegateChromeOS::GetCastConfigDelegate() {
-  if (!cast_config_delegate_)
-    cast_config_delegate_ = CreateCastConfigDelegate();
   return cast_config_delegate_.get();
 }