Add synchronous transaction to wait for setInputWindow to complete (3/n)

Added callback for InputDispatcher to report back to SF.

Pass in an interface callback to setInputWindows so InputDispatcher can send
a response when setInputWindows has completed. The callback can be null
so InputDispatcher knows not to send a response on every setInputWindows
call.

Bug: 123041491
Test: Builds, runs
Change-Id: I18b28141a0bb5f2e1ffb406d601dc7822ca89ecd