cheets: implement cros side of WallpaperManagerService.

components/arc/arc_bridge_host_impl.cc

Index: components/arc/arc_bridge_host_impl.cc
diff --git a/components/arc/arc_bridge_host_impl.cc b/components/arc/arc_bridge_host_impl.cc
index c113d341b1360d84bd14573391cd12d8695743d3..6db6272de2e62c9bddcdba80373abcdbda2dae59 100644
--- a/components/arc/arc_bridge_host_impl.cc
+++ b/components/arc/arc_bridge_host_impl.cc
@@ -188,6 +188,12 @@ void ArcBridgeHostImpl::OnVideoInstanceReady(
   OnInstanceReady(ArcBridgeService::Get()->video(), std::move(video_ptr));
 }
 
+void ArcBridgeHostImpl::OnWallpaperInstanceReady(
+    mojom::WallpaperInstancePtr wallpaper_ptr) {
+  OnInstanceReady(ArcBridgeService::Get()->wallpaper(),
+                  std::move(wallpaper_ptr));
+}
+
 void ArcBridgeHostImpl::OnClosed() {
   DCHECK(thread_checker_.CalledOnValidThread());
   VLOG(1) << "Mojo connection lost";