Revert of Add OBB mounter Mojo interface

components/arc/common/obb_mounter.mojom

-// 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.
-
-module arc.mojom;
-
-interface ObbMounterHost {
-  // Mounts the specified OBB file to the target path, the owner GID will be set
-  // to the specified value.
-  MountObb(string obb_file,
-           string target_path,
-           int32 owner_gid) => (bool success);
-
-  // Unmounts the OBB file mounted to the specifed path.
-  UnmountObb(string target_path) => (bool success);
-};
-
-interface ObbMounterInstance {
-  Init(ObbMounterHost host_ptr);
-};