Resolving createByteBufferFromABuffer null input

It was found that createByteBufferFromABuffer was recieving a NULL buffer in bug
22726278. Based on returning NULL when buffer->base() == NULL, returning NULL
when buffer == NULL. This does not fix bug 22726278 - but address a problem found
while looking into it.

Bug: 22726278
Change-Id: I933b6a4a535d803576a4cdd7a1ffaf4a428c3201