Change the canonical way to include the C bindings headers to <mojo/bindings/*.h>.

mojo/public/c/bindings/interface.h

-// 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.
-
-#ifndef MOJO_PUBLIC_C_BINDINGS_INTERFACE_H_
-#define MOJO_PUBLIC_C_BINDINGS_INTERFACE_H_
-
-#include <mojo/macros.h>
-#include <mojo/system/handle.h>
-#include <stdint.h>
-
-MOJO_BEGIN_EXTERN_C
-
-// |MojomInterfaceData| represents a handle to an interface; in particular, this
-// is the client side of the interface where messages are sent and responses are
-// received. When encoded, |handle| represents the index into an array of
-// handles. The encoded version of an invalid handle is '-1' of MojoHandle type.
-struct MojomInterfaceData {
-  MojoHandle handle;
-  uint32_t version;
-};
-MOJO_STATIC_ASSERT(sizeof(struct MojomInterfaceData) == 8,
-                   "struct MojomInterfaceData must be 8 bytes.");
-
-MOJO_END_EXTERN_C
-
-#endif  // MOJO_PUBLIC_C_BINDINGS_INTERFACE_H_