title: [ExoPlayer]Delete one media cache use SimpleCache and DefaultDatabaseProvider
body: <p>The <code>com.google.android.exoplayer2.upstream.cache.SimpleCache</code> class provides a static method (<code>com.google.android.exoplayer2.upstream.cache.SimpleCache#delete</code>) to delete all cached data. Now I want to delete the cache of only one media. Is there any way to do it?</p>
  <p>like this:</p>
  <pre class="lang-java prettyprint-override"><code>public static void deleteOneMediaCache(MediaItem mediaItem){
  ...
  }
  </code></pre>