Remove the OnError method from notification delegates.

chrome/browser/chromeos/net/network_portal_notification_controller.h

 // Copyright 2014 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 CHROME_BROWSER_CHROMEOS_NET_NETWORK_PORTAL_NOTIFICATION_CONTROLLER_H_
 #define CHROME_BROWSER_CHROMEOS_NET_NETWORK_PORTAL_NOTIFICATION_CONTROLLER_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "chromeos/network/portal_detector/network_portal_detector.h"
 
 namespace chromeos {
 
 class NetworkState;
 
 class NetworkPortalNotificationController {
  public:
   enum NotificationMetric {
     NOTIFICATION_METRIC_DISPLAYED = 0,
+    // TODO(peter): The ERROR metric is not being used anymore, remove it.
     NOTIFICATION_METRIC_ERROR,
     NOTIFICATION_METRIC_COUNT
   };
 
   enum UserActionMetric {
     USER_ACTION_METRIC_CLICKED,
     USER_ACTION_METRIC_CLOSED,
     USER_ACTION_METRIC_IGNORED,
     USER_ACTION_METRIC_COUNT
   };
@@ skipping 13 matching lines @@
  private:
   // Last network path for which notification was displayed.
   std::string last_network_path_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkPortalNotificationController);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_NET_NETWORK_PORTAL_NOTIFICATION_CONTROLLER_H_