arc: Add InstanceHelper::GetInstanceForMethod()

chrome/browser/chromeos/arc/arc_wallpaper_service.cc

 // 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.
 
 #include "chrome/browser/chromeos/arc/arc_wallpaper_service.h"
 
 #include <vector>
 
 #include "ash/common/wallpaper/wallpaper_controller.h"
 #include "ash/common/wm_shell.h"
@@ skipping 123 matching lines @@
   SetBitmapAsWallpaper(bitmap);
 }
 
 void ArcWallpaperService::OnDecodeImageFailed() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   LOG(ERROR) << "Failed to decode wallpaper image.";
 }
 
 void ArcWallpaperService::OnWallpaperDataChanged() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
-  mojom::WallpaperInstance* instance =
-      GetWallpaperInstance(kMinOnWallpaperChangedVersion);
-  if (!instance)
+  auto* wallpaper_instance =
+      arc_bridge_service()->wallpaper()->GetInstanceForVersion(
+          kMinOnWallpaperChangedVersion, "OnWallpaperChanged");
+  if (!wallpaper_instance)
     return;
-  instance->OnWallpaperChanged();
-}
-
-mojom::WallpaperInstance* ArcWallpaperService::GetWallpaperInstance(
-    uint32_t min_version) {
-  uint32_t version = arc_bridge_service()->wallpaper()->version();
-  if (version < min_version) {
-    VLOG(1) << "ARC wallpaper instance is too old. required: " << min_version
-            << ", actual: " << version;
-    return nullptr;
-  }
-
-  mojom::WallpaperInstance* instance =
-      arc_bridge_service()->wallpaper()->instance();
-  if (!instance)
-    VLOG(2) << "ARC wallpaper instance is not ready.";
-  return instance;
+  wallpaper_instance->OnWallpaperChanged();
 }
 
 }  // namespace arc