Get FileSelect dialog work on athena

athena/activity/public/activity_manager.h

Index: athena/activity/public/activity_manager.h
diff --git a/athena/activity/public/activity_manager.h b/athena/activity/public/activity_manager.h
index 1715cf70fa5479ecb8c42439e117065c65a753f0..946f2eefe56ac520002975c4cd16e4e92ee9819d 100644
--- a/athena/activity/public/activity_manager.h
+++ b/athena/activity/public/activity_manager.h
@@ -7,6 +7,10 @@
 
 #include "athena/athena_export.h"
 
+namespace aura {
+class Window;
+}
+
 namespace athena {
 
 class Activity;
@@ -25,6 +29,10 @@ class ATHENA_EXPORT ActivityManager {
   virtual void AddActivity(Activity* activity) = 0;
   virtual void RemoveActivity(Activity* activity) = 0;
 
+  // Returns the activity that has a |window| as toplevel window, or
+  // NULL if such activity does not exist.
+  virtual Activity* GetActivityForWindow(aura::Window* window) = 0;
+
   // Updates the UI when the task color/title changes.
   virtual void UpdateActivity(Activity* activity) = 0;