We currently create a temporary directory to hold Chrome's user-data-dir each time we launch a web device:

https://github.com/flutter/flutter/blob/master/packages/flutter_tools/lib/src/web/chrome.dart#L81

This means that the position of the chrome window won't be remembered between sessions.
The user will position it, but when they next launch their app, will need to reposition it.

We may instead want to write the the --user-data-dir to the .dart_tool/ dir in the project, or a persistent dir in their home directory?

cc @jonahwilliams