Introduces AppActivity and handler of chrome.shell API.

athena/main/athena_main.cc

Index: athena/main/athena_main.cc
diff --git a/athena/main/athena_main.cc b/athena/main/athena_main.cc
index 537e6621a99d24f764b034a97bfdd36b211f015d..7099bff9448d2215422aa3da4ef109d8c6b2726a 100644
--- a/athena/main/athena_main.cc
+++ b/athena/main/athena_main.cc
@@ -8,6 +8,7 @@
 #include "apps/shell/browser/shell_extension_system.h"
 #include "athena/content/public/content_activity_factory.h"
 #include "athena/content/public/content_app_model_builder.h"
+#include "athena/main/athena_app_window_controller.h"
 #include "athena/main/athena_launcher.h"
 #include "athena/main/placeholder.h"
 #include "base/command_line.h"
@@ -48,7 +49,9 @@ class AthenaBrowserMainDelegate : public apps::ShellBrowserMainDelegate {
   virtual apps::ShellDesktopController* CreateDesktopController() OVERRIDE {
     // TODO(mukai): create Athena's own ShellDesktopController subclass so that
     // it can initialize its own window manager logic.
-    return new apps::ShellDesktopController();
+    apps::ShellDesktopController* desktop = new apps::ShellDesktopController();
+    desktop->SetAppWindowController(new athena::AthenaAppWindowController());
+    return desktop;
   }
 
  private: