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

mojo/public/platform/native/mgl_onscreen_thunks.h

-// Copyright 2015 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.
-
-#ifndef MOJO_PUBLIC_PLATFORM_NATIVE_MGL_ONSCREEN_THUNKS_H_
-#define MOJO_PUBLIC_PLATFORM_NATIVE_MGL_ONSCREEN_THUNKS_H_
-
-#include <MGL/mgl_onscreen.h>
-#include <stddef.h>
-
-// Structure used to bind the interface which manipulates MGL contexts to a
-// DSO to theose of the embedder.
-//
-// This is the ABI between the embedder and the DSO. It can only have new
-// functions added to the end. No other changes are supported.
-#pragma pack(push, 8)
-struct MGLOnscreenThunks {
-  size_t size;  // Should be set to sizeof(MojoMGLOnscreenThunks).
-
-  void (*MGLResizeSurface)(uint32_t width, uint32_t height);
-  void (*MGLSwapBuffers)(void);
-};
-#pragma pack(pop)
-
-// Intended to be called from the embedder. Returns an object initialized to
-// contain pointers to each of the embedder's MGLOnscreenThunks functions.
-inline struct MGLOnscreenThunks MojoMakeMGLOnscreenThunks() {
-  struct MGLOnscreenThunks mgl_onscreen_thunks = {
-      sizeof(struct MGLOnscreenThunks), MGLResizeSurface, MGLSwapBuffers,
-  };
-
-  return mgl_onscreen_thunks;
-}
-
-// Use this type for the function found by dynamically discovering it in
-// a DSO linked with mojo_system. For example:
-// MojoSetMGLOnscreenThunksFn mojo_set_gles2_thunks_fn =
-//     reinterpret_cast<MojoSetMGLOnscreenThunksFn>(
-//         app_library.GetFunctionPointer("MojoSetMGLOnscreenThunks"));
-// The expected size of |mgl_thunks| is returned.
-// The contents of |mgl_thunks| are copied.
-typedef size_t (*MojoSetMGLOnscreenThunksFn)(
-    const struct MGLOnscreenThunks* mgl_thunks);
-
-#endif  // MOJO_PUBLIC_PLATFORM_NATIVE_MGL_ONSCREEN_THUNKS_H_