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

remoting/android/BUILD.gn

Index: remoting/android/BUILD.gn
diff --git a/remoting/android/BUILD.gn b/remoting/android/BUILD.gn
index a933e3d6061d3bc8d24ff6650c121a1e1761ea89..9653def81ef90dabc96eb2e708f16fc7bfcc531d 100644
--- a/remoting/android/BUILD.gn
+++ b/remoting/android/BUILD.gn
@@ -70,7 +70,11 @@ remoting_localize("remoting_apk_manifest") {
     "java/AndroidManifest.xml.jinja2",
   ]
   locales = [ "en" ]
-  defines = [ "ENABLE_CARDBOARD=$enable_cardboard" ]
+  if (remoting_enable_cardboard) {
+    defines = [ "ENABLE_CARDBOARD=1" ]
+  } else {
+    defines = [ "ENABLE_CARDBOARD=0" ]
+  }
   variables = [ branding_path ]
   output = "$root_gen_dir/remoting/android/{{source_name_part}}"
 }