This change enables the input dispatcher to send multiple touch
events to an application without waiting for them to be acknowledged.
Essentially this is a variation on the old streaming optimization
but it is much more comprehensive. Event dispatch will stall as
soon as 0.5sec of unacknowledged events are accumulated or a
focused event (such as a key event) needs to be delivered.
Streaming input events makes a tremendous difference in application
performance. The next step will be to enable batching of input
events on the client side once again.
This is part of a series of changes to improve input system pipelining.
Bug: 5963420
Change-Id: I025df90c06165d719fcca7f63eed322a5cce4a78
cd50850d48