Remove ash::ScopedObserverWithDuplicatedSources

ash/shelf/shelf_window_watcher.h

Index: ash/shelf/shelf_window_watcher.h
diff --git a/ash/shelf/shelf_window_watcher.h b/ash/shelf/shelf_window_watcher.h
index e61cacb5e097ab574609feb00fefe23693eb6d95..cf11ba5cb6b7d1dd3e0ebbca2f4c7205de7ba849 100644
--- a/ash/shelf/shelf_window_watcher.h
+++ b/ash/shelf/shelf_window_watcher.h
@@ -7,8 +7,6 @@
 
 #include <stdint.h>
 
-#include "ash/shelf/scoped_observer_with_duplicated_sources.h"
-#include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/scoped_observer.h"
 #include "ui/aura/window_observer.h"
@@ -139,11 +137,6 @@ class ShelfWindowWatcher : public aura::client::ActivationChangeObserver,
   // Holds removed windows that has an item from default container.
   ScopedObserver<aura::Window, aura::WindowObserver> observed_removed_windows_;
 
-  // Holds all observed activation clients.
-  ScopedObserverWithDuplicatedSources<aura::client::ActivationClient,
-                                      aura::client::ActivationChangeObserver>
-      observed_activation_clients_;
-
   DISALLOW_COPY_AND_ASSIGN(ShelfWindowWatcher);
 };