code: public void addWindow(Activity activity) {
          String name = activity.getTitle().toString();
          if (TextUtils.isEmpty(name)) {
              name = activity.getClass().getCanonicalName() +
                      "/0x" + System.identityHashCode(activity);
          } else {
              name += "(" + activity.getClass().getCanonicalName() + ")";
          }
          addWindow(activity.getWindow().getDecorView(), name);
      }
docs: Invoke this method to register a new view hierarchy.
  
  @param activity The activity whose view hierarchy/window to register
  
  @see #addWindow(View, String)
  @see #removeWindow(Activity)