Replace base::CallbackList with base::ObserverList in CastConfigDelegate

chrome/browser/extensions/api/cast_devices_private/cast_devices_private_api.h

Index: chrome/browser/extensions/api/cast_devices_private/cast_devices_private_api.h
diff --git a/chrome/browser/extensions/api/cast_devices_private/cast_devices_private_api.h b/chrome/browser/extensions/api/cast_devices_private/cast_devices_private_api.h
index 7f4da06c64c332cb563e8ee2cf26122a83abccd0..78905889f533f78f29e5898c41d814e1f9c9f325 100644
--- a/chrome/browser/extensions/api/cast_devices_private/cast_devices_private_api.h
+++ b/chrome/browser/extensions/api/cast_devices_private/cast_devices_private_api.h
@@ -10,6 +10,7 @@
 #include "ash/cast_config_delegate.h"
 #include "base/callback_list.h"
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
 #include "extensions/browser/extension_function.h"
 
@@ -23,10 +24,10 @@ class CastDeviceUpdateListeners : public BrowserContextKeyedAPI {
   // Fetch an instance for the given context.

[stevenjb, 2016/01/12 23:31:49]

s/Fetch/Fetches/ (while you're in here)

[jdufault, 2016/01/12 23:59:22]

Done.

   static CastDeviceUpdateListeners* Get(content::BrowserContext* context);
 
-  // Register a function that will be invoked only when a new device update is
+  // Set the function that will be invoked only when a new device update is

[stevenjb, 2016/01/12 23:31:50]

s/Set/Sets/

[jdufault, 2016/01/12 23:59:22]

Done.

   // available.
-  ash::CastConfigDelegate::DeviceUpdateSubscription RegisterCallback(
-      const ash::CastConfigDelegate::ReceiversAndActivitesCallback& callback);
+  void AddObserver(ash::CastConfigDelegate::Observer* observer);
+  void RemoveObserver(ash::CastConfigDelegate::Observer* observer);
 
   // BrowserContextKeyedAPI implementation:
   static BrowserContextKeyedAPIFactory<CastDeviceUpdateListeners>*
@@ -40,7 +41,7 @@ class CastDeviceUpdateListeners : public BrowserContextKeyedAPI {
   friend class CastDevicesPrivateUpdateDevicesFunction;  // For NotifyCallbacks.
   void NotifyCallbacks(const ReceiverAndActivityList& devices);
 
-  base::CallbackList<void(const ReceiverAndActivityList&)> callback_list_;
+  base::ObserverList<ash::CastConfigDelegate::Observer> observer_list_;
 
   friend class BrowserContextKeyedAPIFactory<CastDeviceUpdateListeners>;