Implement PermissionService::GetNextPermissionChange.

content/public/browser/content_browser_client.h

 // Copyright (c) 2012 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_CONTENT_BROWSER_CLIENT_H_
 #define CONTENT_PUBLIC_BROWSER_CONTENT_BROWSER_CLIENT_H_
 
 #include <map>
 #include <string>
 #include <utility>
@@ skipping 434 matching lines @@
                                        WebContents* web_contents,
                                        const GURL& frame_url,
                                        const GURL& main_frame_url) {}
 
   virtual PermissionStatus GetPermissionStatus(
       PermissionType permission,
       BrowserContext* browser_context,
       const GURL& requesting_origin,
       const GURL& embedding_origin);
 
+  // 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(

[jochen (gone - plz use gerrit), 2015/03/11 16:11:24]

why is this not on browser_context?

[mlamouri (slow - plz ping), 2015/03/18 16:24:40]

All the permission related method live here but I think it would make great
sense to make sense to have a PermissionManager hanging from the BrowserContext
(or move the methods there).

However, it might require some refactoring so it would probably be better in a
follow-up.

+      PermissionType permission,
+      BrowserContext* browser_context,
+      const GURL& requesting_origin,
+      const GURL& embedding_origin,
+      const base::Callback<void(PermissionStatus)>& callback);
+
+  virtual void UnsubscribePermissionStatusChange(
+      BrowserContext* browser_context,
+      int subscription_id) {}
+
   virtual void ResetPermission(PermissionType permission,
                                BrowserContext* browser_context,
                                const GURL& requesting_origin,
                                const GURL& embedding_origin) {}
 
   // Returns true if the given page is allowed to open a window of the given
   // type. If true is returned, |no_javascript_access| will indicate whether
   // the window that is created should be scriptable/in the same process.
   // This is called on the IO thread.
   virtual bool CanCreateWindow(const GURL& opener_url,
@@ skipping 188 matching lines @@
   // Allows an embedder to provide its own ExternalVideoSurfaceContainer
   // implementation.  Return nullptr to disable external surface video.
   virtual ExternalVideoSurfaceContainer*
   OverrideCreateExternalVideoSurfaceContainer(WebContents* web_contents);
 #endif
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_CONTENT_BROWSER_CLIENT_H_