tree 03f3362f7919592e14f2bd56957fc4c722397e26
parent 3425dae8dc63372e8944dce43f7ed2d567512248
author Dianne Hackborn <hackbod@google.com> 1428024335 -0700
committer Dianne Hackborn <hackbod@google.com> 1428025411 -0700

Add quick and dirty async AssistStructure building.

New APIs on ViewAssistStructure all the app to request to
build a sub-tree asynchronously and indicate when it is done
with that.  The overall AssistStructure is now only flattened
and transfered on-demand, when the app receiving it requests
its data -- and at that point we can wait for any asynchronous
building to complete.

New AsyncStructure view is a very simple example of using this
to asynchronously build a child view.

Change-Id: I14f9199bee64915ad3dc80b2190916ec874308af