[Payments] Add PaymentRequest checkout funnel UKMs.

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 75d8a1a22b2c52a6c3f111ac4eae536133bddb2c..f105aabfaa90facca5ab73189f648e99d72b81b1 100644
--- a/tools/metrics/ukm/ukm.xml
+++ b/tools/metrics/ukm/ukm.xml
@@ -11,6 +11,15 @@ 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 reson why it was not.

[Steven Holte, 2017/04/11 21:13:10]

Nit: reson->reason

[sebsg, 2017/04/11 21:29:33]

Done.

+    </summary>
+  </metric>
+</event>
+
 <event name="PageLoad">
   <owner>bmcquade@chromium.org</owner>
   <summary>
@@ -36,9 +45,18 @@ along with a detailed description for each metric.
   </metric>
 </event>
 
-<event name="Autofill.CardUploadDecision">
+<event name="PaymentRequest.CheckoutEvents">
   <owner>sebsg@chromium.org</owner>
-  <metric name="UploadDecision"/>
+  <metric name="CompletionsStatus">
+    <summary>
+      How the Payment Request ended.

[Steven Holte, 2017/04/11 21:13:10]

Reference where the values are defined.

[sebsg, 2017/04/11 21:29:33]

Done.

+    </summary>
+  </metric>
+  <metric name="Events">
+    <summary>
+      The events that occurred during the Payment Request.

[Steven Holte, 2017/04/11 21:13:10]

Maybe mention that this a bitfield of events, and where the bits are defined.

[sebsg, 2017/04/11 21:29:33]

Done.

+    </summary>
+  </metric>
 </event>
 
 </ukm-configuration>