Return events from mappers and InputDevice

We are changing the way android input events are reported from the
InputReader. Previously, the process was opaque - anywhere in the code
you were allowed to grab the listener and send events to it. Now, the
flow changes - you will have to explicitly return the events back to the
caller.

With the new approach, InputReader will ultimately be the one
dispatching the events to the listener.

Bug: 211379801
Test: atest inputflinger_tests
Change-Id: I2318ad1220fa66b197ca2a49b8625afcfb45103f
diff --git a/services/inputflinger/tests/fuzzers/SwitchInputFuzzer.cpp b/services/inputflinger/tests/fuzzers/SwitchInputFuzzer.cpp
index e76bd72..7416ce9 100644
--- a/services/inputflinger/tests/fuzzers/SwitchInputFuzzer.cpp
+++ b/services/inputflinger/tests/fuzzers/SwitchInputFuzzer.cpp
@@ -46,7 +46,7 @@
                                       type,
                                       code,
                                       fdp->ConsumeIntegral<int32_t>()};
-                    mapper.process(&rawEvent);
+                    std::list<NotifyArgs> unused = mapper.process(&rawEvent);
                 },
                 [&]() -> void {
                     mapper.getSwitchState(fdp->ConsumeIntegral<uint32_t>(),