ACTIONS
=======

 * "activate-transfer"
   Description: default action when tapping a transfer menuitem.
   For example, tapping a running transfer pauses it. Tapping a paused
   transfer resumes it.
   State: None
   Parameter: s an opaque uid to specify which transer to use.
                This uid comes from the menuitems' x-canonical-uid property.

 * "cancel-transfer"
 * "pause-transfer"
 * "resume-transfer"
 * "open-transfer"
 * "open-app-transfer"
   Description: actions that operate on a single transfer.
   State: None
   Parameter: s an opaque uid to specify which transer to use.
                This uid comes from the menuitems' x-canonical-uid property.

 * "pause-all"
 * "resume-all"
 * "clear-all"
   Description: actions that operate on all transfers.
   State: None
   Parameter: None

 * "transfer-state.$UID" (where $UID matches the x-canonical-uid properties)
   Description: An action whose state provides a transfer's transient properties.
                This is a dict whose key/value pairs are:
                * "percent"      d percent of the progress complete, [0.0 ... 1.0]
                * "seconds-left" i percent done. NB: Not set if no ETA is available.
                * "state"        i int value matching the Transfer::State enum
                                   from transfer-indicator/include/transfer/transfer.h
   Parameter: none. invoking this action has no effect.


CUSTOM MENUITEMS
================

See https://docs.google.com/a/canonical.com/document/d/1OyHUg_uUfmhDNa-9UrMc1tZ_eH_99PEU_V2l1YFA1UY/edit#
for visual mockups of how these should look.

 * Transfer
   - x-canonical-type         s "com.canonical.indicator.transfer"
   - x-canonical-uid          s the transfer's unique identifier string
   - icon                     v the icon for the app receiving the download
   - label                    s human-readable string describing the transfer

 * Bulk Action Menuitem
   This behaves like a normal text menuitem but is rendered differently;
   see the the "Pause all" / "Clear all" buttons in the mockup linked above.
   - x-canonical-type         s "com.canonical.indicator.button-section"
   - label                    s label (e.g., "Successful Transfers")
   - x-canonical-extra-label  s action label (e.g., "Clear All")

