Traverse and compare view hierarchy with assist structure.

Wait until the layout of the third party app has finished being drawn
before starting the VoiceInteractionSession.
View traversal compares positions, scroll positions, widths, heights,
text, IDs, and hierarchy structure between the Assist Structure and
the view rendered to match that or the test third party app.

Bug: 21668302

Change-Id: I0167bdf6afb242ed8a7440ab021e16fc20b608c2
23 files changed