Revert of cheets: implement cros side of WallpaperManagerService.

components/arc/common/wallpaper.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.
-//
-// Next MinVersion: 1
-
-module arc.mojom;
-
-// Handles wallpaper calls from ARC in Chrome.
-// Next method ID:2
-interface WallpaperHost {
-  // Gets current wallpaper encoded in PNG and send it back to ARC.
-  GetWallpaper@0() => (array<uint8> wallpaper);
-
-  // Sets an image from ARC as the wallpaper.
-  // |png_data| is a PNG encoded wallpaper image.
-  SetWallpaper@1(array<uint8> png_data);
-};
-
-// Connects with container side to publish wallpaper related intents.
-// Next method ID:1
-interface WallpaperInstance {
-  // Establishes communication with the container side.
-  Init@0(WallpaperHost host_ptr);
-};