Merge "Metadata: Add audio_metadata_byte_string_len." am: 948f14d101 am: cfb138de15 am: fa7215f61e

Original change: https://android-review.googlesource.com/c/platform/system/media/+/1692727

Change-Id: I6bb85cfa89bdca41088f1b89a4338db896a29a7c