base

Tell system server whether the app handled input events.

Refactored ViewRoot, NativeActivity and related classes to tell the
dispatcher whether an input event was actually handled by the application.

This will be used to move more of the global default key processing
into the system server instead of the application.

Change-Id: If06b98b6f45c543e5ac5b1eae2b3baf9371fba28