athena: Add the concept of Activity and related managers.

athena/screen/background_controller.cc

Index: athena/screen/background_controller.cc
diff --git a/athena/screen/background_controller.cc b/athena/screen/background_controller.cc
index 53cf3e249112ca1da3a27ced2569aab0dec865b9..dd7f6cc4470e44df6ed45140de78213c5b0a12f2 100644
--- a/athena/screen/background_controller.cc
+++ b/athena/screen/background_controller.cc
@@ -25,16 +25,20 @@ class BackgroundView : public views::View {
 
   // views::View
   virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE {
-    canvas->DrawImageInt(image_,
-                         0,
-                         0,
-                         image_.width(),
-                         image_.height(),
-                         0,
-                         0,
-                         width(),
-                         height(),
-                         true);
+    if (!image_.isNull()) {
+      canvas->DrawImageInt(image_,
+                           0,
+                           0,
+                           image_.width(),
+                           image_.height(),
+                           0,
+                           0,
+                           width(),
+                           height(),
+                           true);
+    } else {
+      canvas->DrawColor(SK_ColorRED);
+    }
   }
 
  private: