@Override
    public String toString() {
      return Objects.toStringHelper(this)
          .add("imageCacheKey", mImageCacheKey)
          .add("frameIndex", mFrameIndex)
          .toString();
    }
Facade to the image memory cache for frames of an animated image.

<p>Each animated image should have its own instance of this class.
animated-base/src/main/java/com/facebook/imagepipeline/animated/impl/AnimatedFrameCache.java