Prefer AES when hardware acceleration is available

ChaCha20-Poly1305 is more efficient in software, but many modern CPUs
have acceleration for AES which makes AES-GCM the more preferable choice
in terms of throughput and battery consumption (i.e., less CPU cycles
per byte).

Bug: 26945889
Change-Id: I2b5fac1b8f1efec77fd8d847643d71902eb943e3
2 files changed