code: public void start(GVROnFinish finishCallback)
      {
          if (mAnimations.size() == 0)
          {
              return;
          }
          mIsRunning = true;
          for (int i = 0; i < mAnimations.size(); ++i)
          {
              GVRAnimation anim = mAnimations.get(i);
              anim.reset();
              if (i == 0)
              {
                  anim.setOnFinish(finishCallback);
              }
              else
              {
                  anim.setOnFinish(null);
              }
              anim.start(getGVRContext().getAnimationEngine());
          }
      }
docs: Starts all of the animations in this animator.
  @see GVRAnimator#reset()
  @see GVRAnimationEngine#start(GVRAnimation)