gpu::mojom::Mailbox: Remove unnecessary ArrayTraits IsNull/SetToNull methods

gpu/ipc/common/mailbox_struct_traits.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/ipc/common/mailbox_struct_traits.h"
 
 namespace mojo {
 
 // static
-bool ArrayTraits<MailboxName>::IsNull(const MailboxName& b) {
-  return b.data == nullptr;
-}
-
-// static
-void ArrayTraits<MailboxName>::SetToNull(MailboxName* b) {
-  b->data = nullptr;
-}
-
-// static
 size_t ArrayTraits<MailboxName>::GetSize(const MailboxName& b) {
   return GL_MAILBOX_SIZE_CHROMIUM;
 }
 
 // static
 int8_t* ArrayTraits<MailboxName>::GetData(MailboxName& b) {
   return b.data;
 }
 
 // static
@@ skipping 27 matching lines @@
 // static
 bool StructTraits<gpu::mojom::Mailbox, gpu::Mailbox>::Read(
     gpu::mojom::MailboxDataView data,
     gpu::Mailbox* out) {
   MailboxName mailbox_name;
   mailbox_name.data = &out->name[0];
   return data.ReadName(&mailbox_name);
 }
 
 }  // namespace mojo