Merge "MemoryHeapBase: Map as read-only when needed" am: 6ccc9f3873 am: a7b6181457 am: 30fc85cb77 am: fd4d617c84

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

Change-Id: Idc6f56840f531294e08759c303215d26dccc8966