Added histograms to https://codereview.chromium.org/207553008/.

chrome/renderer/net/net_error_helper_core.h

 // Copyright 2013 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_RENDERER_NET_NET_ERROR_HELPER_CORE_H_
 #define CHROME_RENDERER_NET_NET_ERROR_HELPER_CORE_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 195 matching lines @@
 
   bool auto_reload_enabled_;
   scoped_ptr<base::Timer> auto_reload_timer_;
 
   // Is the browser online?
   bool online_;
 
   int auto_reload_count_;
   bool can_auto_reload_page_;
 
-  // Non-NO_BUTTON only when a navigation has been initiated from the error
-  // page.  Used to detect when such navigations result in errors.
+  // This value is set only when a navigation has been initiated from
+  // the error page.  It is used to detect when such navigations result
+  // in errors.
   Button navigation_from_button_;
 };
 
 #endif  // CHROME_RENDERER_NET_NET_ERROR_HELPER_CORE_H_