Restore to user selected wallpaper after browser crash

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index b5fc9cfaf0a2342552784cf963b08b774368d0c4..54231d562c33801e1f92c2f94e51d49b2fa6a1fe 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -51,6 +51,7 @@ class ShellDelegate;
 class ShellObserver;
 class SystemTrayDelegate;
 class SystemTray;
+class UserWallpaperDelegate;
 class VideoDetector;
 class WindowCycleController;
 
@@ -190,6 +191,9 @@ class ASH_EXPORT Shell : public aura::MonitorObserver {
 
   ShellDelegate* delegate() { return delegate_.get(); }
   SystemTrayDelegate* tray_delegate() { return tray_delegate_.get(); }
+  UserWallpaperDelegate* user_wallpaper_delegate() {
+    return user_wallpaper_delegate_.get();
+  }
 
   Launcher* launcher() { return launcher_.get(); }
 
@@ -256,6 +260,7 @@ class ASH_EXPORT Shell : public aura::MonitorObserver {
 
   scoped_ptr<ShellDelegate> delegate_;
   scoped_ptr<SystemTrayDelegate> tray_delegate_;
+  scoped_ptr<UserWallpaperDelegate> user_wallpaper_delegate_;
 
   scoped_ptr<Launcher> launcher_;