Drop android_sdk_downloader in favor of cipd

[dnfield]

Fixes flutter/flutter#27967

CIPD was actually much easier to implement for this than I initially thought. I've created the packages for Linux and Mac here: https://chrome-infra-packages.appspot.com/p/flutter/android

I've also added bash scripts to help with creating new ones in the future.

[dnfield]

This will fail until we either rebuild the GKE container or land #8098

It's hitting up against flutter/flutter#29013

[jdunn010]

ran into a problem trying to fetch the ndk dependency. not sure what i am doing wrong, any suggestion much appreciated!

`ubuntu-18.04@ip:~/engine$ gclient sync
Syncing projects: 100% (90/90), done.

________ running 'cipd ensure -log-level error -root /home/ubuntu/engine -ensure-file /tmp/tmpzxvmWX.ensure' in '.'
[P18934 01:31:27.259 client.go:1375 E] cipd: failed to fetch flutter/android/ndk/linux-amd64:4PIz5-1td4npawLNyYi6H15qa0WjEVeY5dBDS68c_SAC - failed to download the package file after multiple attempts
[P18934 01:31:27.290 client.go:1560 E] Failed to install flutter/android/ndk/linux-amd64:4PIz5-1td4npawLNyYi6H15qa0WjEVeY5dBDS68c_SAC - failed to download the package file after multiple attempts
Error: failed to update packages, see the log.
Error: Command 'cipd ensure -log-level error -root /home/ubuntu/engine -ensure-file /tmp/tmpzxvmWX.ensure' returned non-zero exit status 1
`

[dnfield]

I've seen that when Google cloud had an issue last week. Do you have the full logs?

[jdunn010]

i think it may actually have been some sort of "user error". I deleted the .cipd directory and re-ran to pull logs for you and it seems to have worked fine! Thanks a lot for such quick response and fixing it!
This is where it ended up, so I think it is all ok:

---------------------------------------- ________ running '/usr/bin/python src/build/landmines.py' in '/home/ubuntu/engine' ________ running '/usr/bin/python src/tools/dart/update.py' in '/home/ubuntu/engine' ________ running '/usr/bin/python src/flutter/tools/android_support/download_android_support.py' in '/home/ubuntu/engine' ________ running '/usr/bin/python src/tools/buildtools/update.py' in '/home/ubuntu/engine' Bootstrapping cipd client for linux-amd64... ######################################################################### 100.0%######################################################################### 100.0% Hook '/usr/bin/python src/tools/buildtools/update.py' took 63.13 secs ________ running '/usr/bin/python flutter/tools/generate_package_files.py' in '/home/ubuntu/engine/src/' ________ running '/usr/bin/python src/tools/remove_stale_pyc_files.py src/tools' in '/home/ubuntu/engine'

[dnfield]

It may have just been a temporary service failure too. Glad it's working now