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 (|navigation_from_button_ != NO_BUTTON|) only

[jar (doing other things), 2014/04/23 01:58:51]

nit: I actually like the new prose much better... but would prefer to omit the
pseudo code (as I waste too much time reading the double negative... and don't
get more out of it that the prose).

This value is set only when a navigation has been initiated from the error page.

YMMV... not worth arguing.  The prose helped me a lot. thx!

[Randy Smith (Not in Mondays), 2014/04/23 18:36:59]

Yeah, I wasn't sure that everyone would realize that "NO_BUTTON" is the same as
not set.  But It's clear enough, and I agree with you the text is better without
the pseudo-code.  Done.

+  // 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_