cheets: add wallpaper observer to arc_wallpaper_service.

chrome/browser/chromeos/arc/arc_wallpaper_service.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 CHROME_BROWSER_CHROMEOS_ARC_ARC_WALLPAPER_SERVICE_H_
 #define CHROME_BROWSER_CHROMEOS_ARC_ARC_WALLPAPER_SERVICE_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <set>
 #include <vector>
 
+#include "ash/common/wallpaper/wallpaper_controller_observer.h"
 #include "base/macros.h"
 #include "chrome/browser/image_decoder.h"
 #include "components/arc/arc_service.h"
 #include "components/arc/common/wallpaper.mojom.h"
 #include "components/arc/instance_holder.h"
 #include "mojo/public/cpp/bindings/binding.h"
 
 class SkBitmap;
 
 namespace arc {
 
 // Lives on the UI thread.
 class ArcWallpaperService
     : public ArcService,
+      public ash::WallpaperControllerObserver,
       public ImageDecoder::ImageRequest,
       public InstanceHolder<mojom::WallpaperInstance>::Observer,
       public mojom::WallpaperHost {
  public:
   explicit ArcWallpaperService(ArcBridgeService* bridge_service);
   ~ArcWallpaperService() override;
 
   // InstanceHolder<mojom::WallpaperInstance>::Observer overrides.
   void OnInstanceReady() override;
 
   // mojom::WallpaperHost overrides.
   // TODO(muyuanli): change callback prototype when use_new_wrapper_types is
   // updated and merge them with the functions below.
   void SetWallpaper(mojo::Array<uint8_t> png_data) override;
   void GetWallpaper(const GetWallpaperCallback& callback) override;
 
   // ImageDecoder::ImageRequest implementation.
   void OnImageDecoded(const SkBitmap& bitmap) override;
   void OnDecodeImageFailed() override;
 
+  // WallpaperControllerObserver implementation.
+  void OnWallpaperDataChanged() override;
+
  private:
+  bool CheckWallpaperInstanceVersion(uint32_t version_need);
+
   mojo::Binding<mojom::WallpaperHost> binding_;
   DISALLOW_COPY_AND_ASSIGN(ArcWallpaperService);
 };
 
 }  // namespace arc
 
 #endif  // CHROME_BROWSER_CHROMEOS_ARC_ARC_WALLPAPER_SERVICE_H_