Add brightness/grayscale animations and use them for OOBE boot transition

ash/desktop_background/desktop_background_controller.h

Index: ash/desktop_background/desktop_background_controller.h
diff --git a/ash/desktop_background/desktop_background_controller.h b/ash/desktop_background/desktop_background_controller.h
index acdd7cf760d48bbd73ed3b15da073f4fbbe3b505..b575654bdd60a65231d974e51d94eb54d41cd78e 100644
--- a/ash/desktop_background/desktop_background_controller.h
+++ b/ash/desktop_background/desktop_background_controller.h
@@ -7,6 +7,7 @@
 
 #include "ash/ash_export.h"
 #include "ash/desktop_background/desktop_background_resources.h"
+#include "ash/wm/window_animations.h"
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
@@ -24,6 +25,9 @@ class UserWallpaperDelegate {
  public:
   virtual ~UserWallpaperDelegate() {}
 
+  // Returns type of window animation that should be used when showin wallpaper.
+  virtual ash::WindowVisibilityAnimationType GetAnimationType() = 0;
+
   // Initialize wallpaper.
   virtual void InitializeWallpaper() = 0;