Implement delete methods

Test: New tests in this patch, IpMemoryStore*Tests
Bug: 146460486
Change-Id: Ibda8eeb917c05876e06e78ae600acd626ca94749
Merged-In: I8680164cf34bae2fac1f5431c03a3369dd6318ab
(cherry picked from commit 4f81f357bce66c9fca13242d83267ae89cd43f1d, aosp/1311637)
25 files changed