Merge "Add MOUNT_FLAG_VISIBLE to visible stub volumes" am: d8e3e07264 am: eba787f7a5 am: 8187197857

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1536320

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I31f8f93fa974f9ee7aa785fd89c45ec5c43dc0bb