Implement RevokePermission() method in PermissionService.

chrome/browser/content_settings/permission_context_base.h

Index: chrome/browser/content_settings/permission_context_base.h
diff --git a/chrome/browser/content_settings/permission_context_base.h b/chrome/browser/content_settings/permission_context_base.h
index d2370c7a585f9fbc5d92243d18fb7d92ba4b9694..4a38f190ec8ea297233dcce45291cbc64f0a20ee 100644
--- a/chrome/browser/content_settings/permission_context_base.h
+++ b/chrome/browser/content_settings/permission_context_base.h
@@ -69,6 +69,11 @@ class PermissionContextBase : public KeyedService {
       const GURL& requesting_origin,
       const GURL& embedding_origin) const;
 
+  // Revokes the permission and returns the new content setting value for it.
+  virtual ContentSetting RevokePermission(
+      const GURL& requesting_origin,
+      const GURL& embedding_origin);
+
   // Withdraw an existing permission request, no op if the permission request
   // was already cancelled by some other means.
   virtual void CancelPermissionRequest(content::WebContents* web_contents,