Fix enable_cardboard/enable_cast for GN build of remoting/android.

remoting/remoting_options.gni

Index: remoting/remoting_options.gni
diff --git a/remoting/remoting_options.gni b/remoting/remoting_options.gni
index 0cf8f2961956fb09e9c0705d67492fe2c933a6a4..0dcd4c97d4bdf3128d0cc455103460ce2400828e 100644
--- a/remoting/remoting_options.gni
+++ b/remoting/remoting_options.gni
@@ -11,17 +11,17 @@ declare_args() {
 
   # Set this to enable building internal AppRemoting apps.
   enable_internal_app_remoting_targets = false
-}
 
-# Set this to enable cast mode on the android client.
-enable_cast = false
+  # Set this to enable cast mode on the android client.
+  remoting_enable_cast = false
+
+  # Set this to enable Android Chromoting Cardboard Activity.
+  remoting_enable_cardboard = false
+}
 
 # Set this to use GCD instead of the remoting directory service.
 remoting_use_gcd = 0
 
-# Set this to enable Android Chromoting Cardboard Activity.
-enable_cardboard = false
-
 # Enable the multi-process host on Windows by default.
 if (is_win) {
   remoting_multi_process = 1