@Override
  public int getTimestampMsForFrame(int frameNumber) {
    Preconditions.checkElementIndex(frameNumber, mFrameTimestampsMs.length);
    return mFrameTimestampsMs[frameNumber];
  }
An {@link AnimatedDrawableBackend} that renders {@link AnimatedImage}.
animated-base/src/main/java/com/facebook/imagepipeline/animated/impl/AnimatedDrawableBackendImpl.java