Logs all reasons card upload was not offered in UKM and UMA.

tools/metrics/ukm/ukm.xml

 <!--
 Copyright 2017 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.
 -->
 
 <!--
 This file is used to generate a comprehensive list of Chrome UKM metrics
 along with a detailed description for each metric.
 -->
 
 <ukm-configuration>
 
 <event name="Autofill.CardUploadDecision">
   <owner>sebsg@chromium.org</owner>
   <metric name="UploadDecision">
     <summary>
-      Whether the upload was proposed to the user or the reason why it was not.
+      Whether the upload was proposed to the user or the reasons why it was not.
+      The value is a bitmask of |CardUploadDecisionMetric|.
     </summary>
   </metric>
 </event>
 
 <event name="Autofill.DeveloperEngagement">
   <owner>csashi@google.com</owner>
   <summary>
     Recorded when we parse a form to log whether developer has used autocomplete
-    markup or UPI-VPA hints.
+    markup or UPI-VPA hints. The value is a bitmask of
+    |DeveloperEngagementMetric|.
   </summary>
   <metric name="DeveloperEngagement"/>
 </event>
 
 <event name="Autofill.FormSubmitted">
   <owner>csashi@google.com</owner>
   <summary>
     Recorded when user submits a form.
   </summary>
   <metric name="AutofillFormSubmittedState">
@@ skipping 168 matching lines @@
   <metric name="DeclineCount"/>
   <metric name="EventType"/>
   <metric name="IgnoreCount"/>
   <metric name="RankerResponse"/>
   <metric name="RankerVersion"/>
   <metric name="SourceLanguage"/>
   <metric name="TargetLanguage"/>
 </event>
 
 </ukm-configuration>