[RESTRICT AUTOMERGE] Fix potential decrypt destPtr overflow. am: 3c9044cdef

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/13461242

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I96d1fc7338a3a2d4d344e8e7ee3aa50077d3ec69