Fix NeverReady to never be ready

Also removed AlwaysReady since no one uses it.

PiperOrigin-RevId: 696590677

pkg/waiter/waiter.go

@@ -259,45 +259,23 @@ func (q *Queue) IsEmpty() bool {
 	return q.list.Front() == nil
 }
 
-// AlwaysReady implements the Waitable interface but is always ready. Embedding
-// this struct into another struct makes it implement the boilerplate empty
-// functions automatically.
-type AlwaysReady struct {
-}
-
-// Readiness always returns the input mask because this object is always ready.
-func (*AlwaysReady) Readiness(mask EventMask) EventMask {
-	return mask
-}
-
-// EventRegister doesn't do anything because this object doesn't need to issue
-// notifications because its readiness never changes.
-func (*AlwaysReady) EventRegister(*Entry) error {
-	return nil
-}
-
-// EventUnregister doesn't do anything because this object doesn't need to issue
-// notifications because its readiness never changes.
-func (*AlwaysReady) EventUnregister(e *Entry) {
-}
-
 // NeverReady implements the Waitable interface but is never ready. Otherwise,
 // this is exactly the same as AlwaysReady.
 type NeverReady struct {
 }
 
-// Readiness always returns the input mask because this object is always ready.
-func (*NeverReady) Readiness(mask EventMask) EventMask {
-	return mask
+// Readiness always returns 0 because this object is never ready.
+func (*NeverReady) Readiness(EventMask) EventMask {
+	return 0
 }
 
 // EventRegister doesn't do anything because this object doesn't need to issue
 // notifications because its readiness never changes.
-func (*NeverReady) EventRegister(e *Entry) error {
+func (*NeverReady) EventRegister(*Entry) error {
 	return nil
 }
 
 // EventUnregister doesn't do anything because this object doesn't need to issue
 // notifications because its readiness never changes.
-func (*NeverReady) EventUnregister(e *Entry) {
+func (*NeverReady) EventUnregister(*Entry) {
 }