Merge "Expose a static method for computing hash tree size" am: 633391cdb5 am: e60fc3f4f2 am: 26026b78d0

Original change: https://android-review.googlesource.com/c/platform/system/extras/+/1692746

Change-Id: I1c09bd4ed4519d58a17b33f78e38b5c7d184a21f