Handle expired OAuth tokens

[James Henstridge]

For most online services, you can only determine that your credentials have expired by attempting to make an API call. So we need some way for the provider specific code to inform us that this has happened and react appropriately.

This should look something like:

1. provider code signals problem via a CredentialsExpiredError exception

2. When Handler sees this error, rather than reporting it to the client, ask online-accounts to authenticate again with interactive=true and invalidateCachedReply=true.

3. If the authenticate() call returns an error, send an error to the client. If it succeeds, call the handler callback a second time with the new credentials.

4. If the provider code throws CredentialsExpired a second time, report an error to the user.

[Launchpad Janitor (janitor)]

This bug was fixed in the package storage-framework - 0.3+17.04.20170320.1-0ubuntu1

---------------
storage-framework (0.3+17.04.20170320.1-0ubuntu1) zesty; urgency=medium

  [ James Henstridge ]
  * Make providers exit after 30 seconds of inactivity. (LP: #1616758)
  * Add UnauthorizedException to the provider library, so the provider
    can trigger reauthentication of the account and have the request
    restarted. (LP: #1616756)
  * Dynamically add and remove providers as the associated accounts
    are enabled and disabled. (LP: #1616757)
  * Allow creation of storage providers that don't use online-accounts.
    Thisis likely only of interest to the local storage provider.

  [ Michi Henning ]
  * Add a storage provider backed by the local file system.
  * Move unity::storage::provider::Item to its own header file. (LP:
    #1668872)
  * If a provider can't acquire its D-Bus well known name, exit rather
    than throwing a (usually uncaught) exception. (LP: #1604640)

 -- Michi Henning <email address hidden> Mon, 20 Mar 2017 04:51:08 +0000