Merge "Metadata: Add audio_metadata_byte_string_len." am: 948f14d101 am: cfb138de15 am: fa7215f61e am: 0311d9c497

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

Change-Id: I1af2d47caac68e53c8f17402b8a59b3594f62d3b