Account malloc mmaped pages as native heap.

Currently when malloc uses a page rather than brk the heap gets accounted as
ashmem memory. Previously the memory would be accounted as unknown but since
[1] it gets accounted as ashmem. This change makes the accounting see this
memory as being native, ie the same kind of memory we associate with brk.

[1] https://android-review.googlesource.com/#/c/49583/3

Change-Id: I6f496cfeb590268d41d8e047b12cd5c90359e2b0
Fix ListView is not scrolled properly with arrows

According to ListView's layoutChildren logic, it detaches all children
and rebuilds its children based on visible area which might omit
invisible elements in the adapter.

In this case, arrowScroll methods only tries to find next scroll
candidates from its children so user is unable to scroll more with
D-pad.

This fixes the issue by look forward next child among the adapter as
well as children.

Bug: 7346868
Change-Id: I01ab19ad899b5bcb5ab420ddf08c9ffd136933d1