Merge "Bufferpool: add BufferpoolUnitTest" am: 078371bd21 am: d7983edfb3 am: 8fbe889331

Original change: https://android-review.googlesource.com/c/platform/frameworks/av/+/1908156

Change-Id: I1fb159101ca0e3438eb0df33bb4c3d5bf452c21d