Comment 2 for bug 1280169

Here's what I'm planning to implement. For backward compatibility, I will add a new method to the D-Bus API. There will be no changes to existing methods. The new method will be called Information() and will return a dictionary mapping strings to strings. From https://wiki.ubuntu.com/ImageBasedUpgrades/Client

Information()
Like Info(), but returns extended information that includes the last time a CheckForUpdate() was performed. Returns a dictionary of strings-to-strings, where the following keys are currently defined:

current_build_number - The current build number, as a string.
device_name - The device name.
channel_name - The device's current channel.
last_update_date - ISO 8601 UTC format string, with second resolution, e.g. "YYYY-MM-DDTHH:MM:SS"
version_details - comma-separated key-value pairs providing additional version details, e.g. ubuntu=123,mako=456,custom=789
last_check_date - ISO 8601 UTC format string, with second resolution, e.g. "YYYY-MM-DDTHH:MM:SS"

Note that `last_check_date` is the new bit of information that closes this bug. Also note that the version_details value is different than in the Info() method. The client calling Information() must split the returned value itself.