Add a histogram for each time the HTTP Bad UI is shown

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index dae17a73801308a0a11862a349a1b416ae4e99f7..88484191c0ef816759295dbbad52f9b7b99f4f15 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -56094,6 +56094,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Security.HTTPBad.UserWarnedAboutSensitiveInput">
+  <owner>elawrence@chromium.org</owner>
+  <owner>estark@chromium.org</owner>
+  <summary>
+    Counts the number of main-frame navigations on which a &quot;Not
+    secure&quot; warning was shown in the omnibox due to sensitive form fields
+    appearing on HTTP pages. False values indicate the count of times that only
+    a console warning was shown.
+  </summary>
+</histogram>
+
 <histogram name="Security.PageInfo.Action.HttpsUrl.Dangerous"
     enum="WebsiteSettingsAction">
   <owner>estark@chromium.org</owner>