Updates shadow when active window changes

mash/wm/window_manager_application.h

Index: mash/wm/window_manager_application.h
diff --git a/mash/wm/window_manager_application.h b/mash/wm/window_manager_application.h
index 45916ea895233e4f3561a4ea01962ed828425fd0..7253d22fea760a1f8a632512b88e8c6699efa6bb 100644
--- a/mash/wm/window_manager_application.h
+++ b/mash/wm/window_manager_application.h
@@ -37,6 +37,7 @@ namespace wm {
 
 class AcceleratorRegistrarImpl;
 class BackgroundLayout;
+class ShadowController;
 class ShelfLayout;
 class WindowLayout;
 class WindowManagerImpl;
@@ -123,6 +124,8 @@ class WindowManagerApplication
   scoped_ptr<ShelfLayout> shelf_layout_;
   scoped_ptr<WindowLayout> window_layout_;
 
+  scoped_ptr<ShadowController> shadow_controller_;
+
   std::set<AcceleratorRegistrarImpl*> accelerator_registrars_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowManagerApplication);