Modified ActivityView to inject touch events it receives back into
its activity container. The container then injects the event into
the input system along with the display id of the underlying virtual
display.
Enhanced the input system to support concurrent dispatch of touch
events on multiple displays which is required for this to work.
Change-Id: I9cf1870db3be6f99a52ed9a1e3ceafe42c940093
38f96e5020