Implement PermissionService::GetNextPermissionChange.

content/public/browser/permission_manager.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_PUBLIC_BROWSER_PERMISSION_MANAGER_H_
 #define CONTENT_PUBLIC_BROWSER_PERMISSION_MANAGER_H_
 
 #include "content/common/content_export.h"
 #include "content/public/common/permission_status.mojom.h"
 
@@ skipping 25 matching lines @@
       const GURL& requesting_origin,
       const GURL& embedding_origin) = 0;
 
   virtual void ResetPermission(PermissionType permission,
                                const GURL& requesting_origin,
                                const GURL& embedding_origin) = 0;
 
   virtual void RegisterPermissionUsage(PermissionType permission,
                                        const GURL& requesting_origin,
                                        const GURL& embedding_origin) = 0;
+
+  // Runs the given |callback| whenever the |permission| associated with the
+  // pair { requesting_origin, embedding_origin } changes.
+  // Returns the subscription_id to be used to unsubscribe.
+  virtual int SubscribePermissionStatusChange(
+      PermissionType permission,
+      const GURL& requesting_origin,
+      const GURL& embedding_origin,
+      const base::Callback<void(PermissionStatus)>& callback) = 0;
+
+  virtual void UnsubscribePermissionStatusChange(int subscription_id) = 0;
 };
 
 }  // namespace content
 
 #endif // CONTENT_PUBLIC_BROWSER_PERMISSION_MANAGER_H_