docs: public boolean runOnMainThread(final Runnable r) {
          assert handler != null;
          if (!sanityCheck("runOnMainThread " + r)) {
              return false;
          }
  
          Runnable wrapper =  new Runnable() {
              public void run() {
                  FPSCounter.timeCheck("runOnMainThread <START> " + r);
                  r.run();
                  FPSCounter.timeCheck("runOnMainThread <END> " + r);
              }
          };
  
          if (isMainThread()) {
              wrapper.run();
              return true;
          } else {
              return runOnMainThreadNext(wrapper);
          }
      }