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

tools/metrics/ukm/ukm.xml

Index: tools/metrics/ukm/ukm.xml
diff --git a/tools/metrics/ukm/ukm.xml b/tools/metrics/ukm/ukm.xml
index 541f1f6bc6ea3b5166ec6120c58496b55577d051..435d2e8b2cb2d51ed010595d4f452d2f00bf64b1 100644
--- a/tools/metrics/ukm/ukm.xml
+++ b/tools/metrics/ukm/ukm.xml
@@ -15,7 +15,8 @@ along with a detailed description for each metric.
   <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>
@@ -24,7 +25,8 @@ along with a detailed description for each metric.
   <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>