internal/legacy: drop legacy prefix

The legacy prefix made sense when this functionality was part of impl.
Now that it is in its own package called legacy, the legacy prefix is silly.

Change-Id: I9e6ddb6185ce1f701e02768b505e6a05f3986f77
Reviewed-on: https://go-review.googlesource.com/c/152543
Reviewed-by: Herbie Ong <herbie@google.com>
diff --git a/internal/legacy/message.go b/internal/legacy/message.go
index a81bb2e..83e723e 100644
--- a/internal/legacy/message.go
+++ b/internal/legacy/message.go
@@ -19,25 +19,25 @@
 	ptype "github.com/golang/protobuf/v2/reflect/prototype"
 )
 
-// legacyWrapMessage wraps v as a protoreflect.ProtoMessage,
+// wrapMessage wraps v as a protoreflect.ProtoMessage,
 // where v must be a *struct kind and not implement the v2 API already.
-func legacyWrapMessage(v reflect.Value) pref.ProtoMessage {
-	mt := legacyLoadMessageType(v.Type())
+func wrapMessage(v reflect.Value) pref.ProtoMessage {
+	mt := loadMessageType(v.Type())
 	return mt.MessageOf(v.Interface()).Interface()
 }
 
 var messageTypeCache sync.Map // map[reflect.Type]*MessageType
 
-// legacyLoadMessageType dynamically loads a *MessageType for t,
+// loadMessageType dynamically loads a *MessageType for t,
 // where t must be a *struct kind and not implement the v2 API already.
-func legacyLoadMessageType(t reflect.Type) *pimpl.MessageType {
+func loadMessageType(t reflect.Type) *pimpl.MessageType {
 	// Fast-path: check if a MessageType is cached for this concrete type.
 	if mt, ok := messageTypeCache.Load(t); ok {
 		return mt.(*pimpl.MessageType)
 	}
 
 	// Slow-path: derive message descriptor and initialize MessageType.
-	md := legacyLoadMessageDesc(t)
+	md := loadMessageDesc(t)
 	mt := new(pimpl.MessageType)
 	mt.Type = ptype.GoMessage(md, func(pref.MessageType) pref.ProtoMessage {
 		p := reflect.New(t.Elem()).Interface()
@@ -49,9 +49,9 @@
 
 var messageDescCache sync.Map // map[reflect.Type]protoreflect.MessageDescriptor
 
-// legacyLoadMessageDesc returns an MessageDescriptor derived from the Go type,
+// loadMessageDesc returns an MessageDescriptor derived from the Go type,
 // which must be a *struct kind and not implement the v2 API already.
-func legacyLoadMessageDesc(t reflect.Type) pref.MessageDescriptor {
+func loadMessageDesc(t reflect.Type) pref.MessageDescriptor {
 	return messageDescSet{}.Load(t)
 }
 
@@ -108,9 +108,9 @@
 	if _, ok := mv.(pref.ProtoMessage); ok {
 		panic(fmt.Sprintf("%v already implements proto.Message", t))
 	}
-	if md, ok := mv.(legacyMessage); ok {
+	if md, ok := mv.(messageV1); ok {
 		b, idxs := md.Descriptor()
-		fd := legacyLoadFileDesc(b)
+		fd := loadFileDesc(b)
 
 		// Derive syntax.
 		switch fd.GetSyntax() {
@@ -128,7 +128,7 @@
 			m.FullName = m.FullName.Append(pref.Name(md.GetName()))
 		}
 	} else {
-		// If the type does not implement legacyMessage, then the only way to
+		// If the type does not implement messageV1, then the only way to
 		// obtain the full name is through the registry. However, this is
 		// unreliable as some generated messages register with a fork of
 		// golang/protobuf, so the registry may not have this information.
@@ -221,7 +221,7 @@
 		if ev, ok := reflect.Zero(t).Interface().(pref.ProtoEnum); ok {
 			f.EnumType = ev.ProtoReflect().Type()
 		} else {
-			f.EnumType = legacyLoadEnumDesc(t)
+			f.EnumType = loadEnumDesc(t)
 		}
 	}
 	if f.MessageType == nil && (f.Kind == pref.MessageKind || f.Kind == pref.GroupKind) {