Make the fuchsia mojo/public repo the source of truth.

mojo/public/c/lib/bindings/buffer.c

-// 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 <mojo/bindings/buffer.h>
-
-#include <assert.h>
-#include <mojo/bindings/internal/util.h>
-#include <stddef.h>
-
-void* MojomBuffer_Allocate(struct MojomBuffer* buf, uint32_t num_bytes) {
-  assert(buf);
-
-  const uint32_t bytes_used = buf->num_bytes_used;
-  const uint64_t size = MOJOM_INTERNAL_ROUND_TO_8((uint64_t)num_bytes);
-  if (bytes_used + size > buf->buf_size)
-    return NULL;
-
-  buf->num_bytes_used += size;
-  return buf->buf + bytes_used;
-}