Implement PermissionService::GetNextPermissionChange.

content/public/browser/content_browser_client.h

Index: content/public/browser/content_browser_client.h
diff --git a/content/public/browser/content_browser_client.h b/content/public/browser/content_browser_client.h
index c5c3942d749cc211489a01c8b1d6f7f22e961cd5..40636014c13e4de139e28e25e5560f0eeda72458 100644
--- a/content/public/browser/content_browser_client.h
+++ b/content/public/browser/content_browser_client.h
@@ -452,6 +452,20 @@ class CONTENT_EXPORT ContentBrowserClient {
       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,