Fix phantom reference based cleanup of JNI-created buffer

This change allows to safely use PhantomReference to detect
if the memory wrapped by buffer created by JNI NewDirectByteBuffer
is no longer referenced (and therfore safe to free/reuse/alter).

Previously it was not possible without reflection because the buffer
could be collected by GC while the MemoryRef that is actually wrapping
the memory could be still used in derived buffer (for example, result of
asReadOnlyBuffer()).

This is mittigated by adding a reference to orinal DirectByteBuffer in
the MemoryRef, forcing GC to keep the buffer alive as long as MemoryRef
is alive.

Test: BufferTest in CtsLibcoreTestCases
Bug: 62133955
Change-Id: I06601d8b6b6157114a448d3623c35fbb9d4633a2

0 files changed, 0 insertions, 0 deletions