-keep class com.google.android.gms.ads.identifier.AdvertisingIdClient {
   com.google.android.gms.ads.identifier.AdvertisingIdClient$Info getAdvertisingIdInfo(android.content.Context);
}
-keep class com.google.android.gms.ads.identifier.AdvertisingIdClient$Info {
   java.lang.String getId();
   boolean isLimitAdTrackingEnabled();
}