Restore to user selected wallpaper after browser crash

ash/shell/shell_main.cc

 // Copyright (c) 2012 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 <map>
 
 #include "ash/launcher/launcher.h"
 #include "ash/launcher/launcher_delegate.h"
 #include "ash/launcher/launcher_model.h"
 #include "ash/launcher/launcher_types.h"
@@ skipping 212 matching lines @@
       ash::LauncherModel* model) OVERRIDE {
     launcher_delegate_ = new LauncherDelegateImpl(watcher_);
     return launcher_delegate_;
   }
 
   virtual ash::SystemTrayDelegate* CreateSystemTrayDelegate(
       ash::SystemTray* tray) {
     return NULL;
   }
 
+  virtual ash::UserWallpaperDelegate* CreateUserWallpaperDelegate() {
+    return NULL;
+  }
+
  private:
   // Used to update Launcher. Owned by main.
   WindowWatcher* watcher_;
 
   LauncherDelegateImpl* launcher_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(ShellDelegateImpl);
 };
 
 }  // namespace
@@ skipping 36 matching lines @@
   window_watcher.reset();
 
   ash::Shell::DeleteInstance();
 
   aura::Env::DeleteInstance();
 
   ui::CompositorTestSupport::Terminate();
 
   return 0;
 }