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

chrome/renderer/net/net_error_helper_core.h

Index: chrome/renderer/net/net_error_helper_core.h
diff --git a/chrome/renderer/net/net_error_helper_core.h b/chrome/renderer/net/net_error_helper_core.h
index ce053a6f3718ae8c8793f75bfc3fb0f59b7ae7d3..33343512ceecd0bf72c0e5f085d70b2cd43baba2 100644
--- a/chrome/renderer/net/net_error_helper_core.h
+++ b/chrome/renderer/net/net_error_helper_core.h
@@ -213,8 +213,9 @@ class NetErrorHelperCore {
   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_;
 };