InputMapper: pass RawEvent references instead of pointers

We never pass null values here, so changing to references makes this
clearer.

Change-Id: I82d5359e244a93560bcbef477c89fef016168abb
Test: atest inputflinger_test
Test: m checkinput
Test: manually test basic functionality on a multi-touch screen, touchpad, mouse, and drawing tablet
Bug: 245989146
Flag: EXEMPT refactor
diff --git a/services/inputflinger/reader/mapper/MultiTouchInputMapper.h b/services/inputflinger/reader/mapper/MultiTouchInputMapper.h
index 5c173f3..cca2327 100644
--- a/services/inputflinger/reader/mapper/MultiTouchInputMapper.h
+++ b/services/inputflinger/reader/mapper/MultiTouchInputMapper.h
@@ -31,7 +31,7 @@
     ~MultiTouchInputMapper() override;
 
     [[nodiscard]] std::list<NotifyArgs> reset(nsecs_t when) override;
-    [[nodiscard]] std::list<NotifyArgs> process(const RawEvent* rawEvent) override;
+    [[nodiscard]] std::list<NotifyArgs> process(const RawEvent& rawEvent) override;
     [[nodiscard]] std::list<NotifyArgs> reconfigure(nsecs_t when,
                                                     const InputReaderConfiguration& config,
                                                     ConfigurationChanges changes) override;