mash: Migrate wallpaper controllers to ash/common.

ash/aura/wm_root_window_controller_aura.h

Index: ash/aura/wm_root_window_controller_aura.h
diff --git a/ash/aura/wm_root_window_controller_aura.h b/ash/aura/wm_root_window_controller_aura.h
index 65cfe949c2ab808b39467ee2ae32d3c786a7b5ff..17c8b0756e64833ecfe79dc45cc2f7510c01650e 100644
--- a/ash/aura/wm_root_window_controller_aura.h
+++ b/ash/aura/wm_root_window_controller_aura.h
@@ -41,6 +41,8 @@ class ASH_EXPORT WmRootWindowControllerAura : public WmRootWindowController {
       views::Widget::InitParams* init_params) override;
   WmWindow* FindEventTarget(const gfx::Point& location_in_screen) override;
   gfx::Point GetLastMouseLocationInRoot() override;
+  void OnInitialWallpaperAnimationStarted() override;
+  void OnWallpaperAnimationFinished(views::Widget* widget) override;
 
  private:
   friend class RootWindowController;