feat(autocomplete): Confusion around `md-selected-item-change`.

[topherfangio]

Actual Behavior:

• What is the issue? * md-selected-item-change fires more often than expected.
• What is the expected behavior? Users expect the md-selected-item-change event to fire only when an actual item has been selected. It currently fires whenever the selected item changes, even if that is to itself or to a non-item. This typically happens when an item is selected, and then the user types another character in the autocomplete and the md-selected-item-change fires with a value of undefined.

Proposal: *

We should consider adding a separate md-on-select to the <md-autocomplete> that behaves more like the md-on-select from the <md-select> component.

AngularJS Versions: *

• AngularJS Version: N/A
• AngularJS Material Version: 1.1.3

References #3003. References #9970.

[brandonwbrown]

i'm having some confusion about this. when i retrieve data from an http promise and change ctrl.searchText to the result of the promise, i'd expect the selectedItemChange to fire, but it doesn't unless i manually click on the field. only then is the searchText sent correctly and item is selected.