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

gpu/ipc/common/mailbox_struct_traits.cc

Index: gpu/ipc/common/mailbox_struct_traits.cc
diff --git a/gpu/ipc/common/mailbox_struct_traits.cc b/gpu/ipc/common/mailbox_struct_traits.cc
index 2218a839de864553d9e531d47d2e32f91039976b..88577706c2221694e13be7bdb7bd81a01626f888 100644
--- a/gpu/ipc/common/mailbox_struct_traits.cc
+++ b/gpu/ipc/common/mailbox_struct_traits.cc
@@ -7,16 +7,6 @@
 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;
 }