For iOS Chrome, we need to be able to support server-controlled configs for Finch during FirstRun. This exists on other platforms, but not iOS.

There are two main reasons why we require this:
1) A/B experiments for FirstRun UI (can be hard-coded client-side, but this is suboptimal. Client-side workaround recently introduced in https://bugs.chromium.org/p/chromium/issues/detail?id=427823).
2) Being able to have a kill-switch for features/experiments that roll out and need to be dynamically disabled (no way to work around this).

This will likely require bringing up part of the FRE without using any chrome code and then switching to the main FRE once we download the config. We will also need to figure out when we are allowed to fetch the seed compared to when the user confirms the EULA. We should check with Chrome Privacy .