Import downloader code to AOSP. am: c0449c8753 am: 3ebc998629 am: f1a7677242 am: d51fc2721f

Original change: https://android-review.googlesource.com/c/platform/external/downloader/+/1591311

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ie4af46f266fa1539ae9f9a711e7b870df48c268c
tree: 5895b1324176d6021865c54215b35fc311ae4544
  1. src/
  2. LICENSE
  3. METADATA
  4. MODULE_LICENSE_APACHE2
  5. OWNERS