Import jni_generator from root package am: 463ea434c7 am: 2232bd223f am: 6923a9a0cd am: c400e7e2d3

Original change: https://android-review.googlesource.com/c/platform/external/libchrome/+/2237476

Change-Id: I6740d913660a053625af8d99136ac07e8a812d5a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>