Input: Add isStylusToolType() utility function

Using this utility function will ensure we don't forget to check for
both TOOL_TYPE_STYLUS and TOOL_TYPE_ERASER when we are looking to
identify a stylus.

This will cause a behavior change in UnwantedInteractionBlocker, where
TOOL_TYPE_ERASER was not previously considered a stylus tool.

Bug: None
Test: atest inputflinger_tests
Change-Id: I3dae9b5037d7ac08a5672c6e4d6e3b62ee2bd352
diff --git a/services/inputflinger/dispatcher/InputDispatcher.cpp b/services/inputflinger/dispatcher/InputDispatcher.cpp
index f698217..4091310 100644
--- a/services/inputflinger/dispatcher/InputDispatcher.cpp
+++ b/services/inputflinger/dispatcher/InputDispatcher.cpp
@@ -479,8 +479,7 @@
 
 bool isPointerFromStylus(const MotionEntry& entry, int32_t pointerIndex) {
     return isFromSource(entry.source, AINPUT_SOURCE_STYLUS) &&
-            (entry.pointerProperties[pointerIndex].toolType == AMOTION_EVENT_TOOL_TYPE_STYLUS ||
-             entry.pointerProperties[pointerIndex].toolType == AMOTION_EVENT_TOOL_TYPE_ERASER);
+            isStylusToolType(entry.pointerProperties[pointerIndex].toolType);
 }
 
 // Determines if the given window can be targeted as InputTarget::FLAG_FOREGROUND.