[Athena] Add status icons and system time to the desktop background

athena/system/public/system_ui.h

Index: athena/system/public/system_ui.h
diff --git a/athena/system/public/system_ui.h b/athena/system/public/system_ui.h
index 0032c5483cd176e678549f285b13e71ecc6c1f4b..4cd04d02106b3a7a6a47689066275d3dace3047f 100644
--- a/athena/system/public/system_ui.h
+++ b/athena/system/public/system_ui.h
@@ -12,15 +12,33 @@ namespace base {
 class TaskRunner;
 }
 
+namespace gfx {
+class ImageSkia;
+}
+
+namespace views {
+class View;
+}
+
 namespace athena {
 
 class ATHENA_EXPORT SystemUI {
  public:
   // Creates and deletes the singleton object of the SystemUI implementation.
   static SystemUI* Create(scoped_refptr<base::TaskRunner> io_task_runner);
+  static SystemUI* Get();
   static void Shutdown();
 
   virtual ~SystemUI() {}
+
+  // Sets the background image.
+  virtual void SetBackgroundImage(const gfx::ImageSkia& image) = 0;
+
+  // Creates a view which displays the time.
+  virtual views::View* CreateTimeView() = 0;
+
+  // Creates a view which displays status icons and debug information.
+  virtual views::View* CreateStatusIconView() = 0;
 };
 
 }  // namespace athena