Use correct padding for nine-patch drawables

Nine-patch drawables have their padding defined as part of the nine
patch chunk. This correctly extracts the padding from the chunk and sets
it to the drawable.

Bug: 195737352
Test: Updated layoutlib tests
Change-Id: I2412b59c905cdb9de2247ae5fe5cdbcfcd6bb79f
(cherry picked from commit 6af69b033acb84fd5c61b7aa98b65bd7249f4077)
Merged-In: I2412b59c905cdb9de2247ae5fe5cdbcfcd6bb79f
5 files changed