Merge "MemoryHeapBase: Map as read-only when needed" am: 6ccc9f3873 am: a7b6181457 am: 30fc85cb77

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/1474377

Change-Id: Id72e323905ef26cebb6c1fdf4d960296a86f0f7a