Currently, LocalBackend/ExtensionHost doesn't invoke the profile change callback for the initial profile.
Since the initial profile may vary depending on loaded extensions and applied policy settings,
it can't be reliably determined until all extensions are initialized. Additionally, some extensions
may asynchronously trigger a switch to the "best" profile (based on system state and policy settings) during
initialization.
We intended to address these issues as part of the ongoing profileManager/LocalBackend refactoring,
but the changes didn't land in time for the v1.84 release and the Taildrop refactoring.
In this PR, we update the Taildrop extension to retrieve the current profile at initialization time
and handle it as a profile change.
We also defer extension initialization until LocalBackend has started, since the Taildrop extension
already relies on this behavior (e.g., it requires clients to call SetDirectFileRoot before Init).
Fixes#15970
Updates #15812
Updates tailscale/corp#28449
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Taildrop has never had an end-to-end test since it was introduced.
This adds a basic one.
It caught two recent refactoring bugs & one from 2022 (0f7da5c7dc0).
This is prep for moving the rest of Taildrop out of LocalBackend, so
we can do more refactorings with some confidence.
Updates #15812
Change-Id: I6182e49c5641238af0bfdd9fea1ef0420c112738
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
