Uses fine grained histogram buckets for CVC errors.

tools/metrics/histograms/enums.xml

Index: tools/metrics/histograms/enums.xml
diff --git a/tools/metrics/histograms/enums.xml b/tools/metrics/histograms/enums.xml
index e7ab6072226259de232d5a86d81b90b7a2263634..086e151c9d6df72e9af8235f878716840bbb01a3 100644
--- a/tools/metrics/histograms/enums.xml
+++ b/tools/metrics/histograms/enums.xml
@@ -1614,17 +1614,17 @@ uploading your change for review.  These are checked by presubmit scripts.
 
 <enum name="AutofillCardUploadDecisionMetric" type="int">
   <int value="0" label="Upload offered"/>
-  <int value="1" label="Upload not offered, no CVC detected"/>

[sebsg, 2017/05/05 15:15:31]

You should keep the ones that don't change like "no address available" to the
same value. The reason being that when you'll analyze the metrics, you'll filter
by bucket. In the case, between two versions you will change the bucket meaning,
which is bad.

What I suggest is 

1) Either deprecate the old bucket 1 (Put name as deprecated) and put the others
at the bottom.

2) if you feel like "CVC field not detected" is equivalent to "... no CVC
detected" you can change the name of that bucket, but still put the others at
the bottom.

I lean towards solution 1)

[csashi, 2017/05/05 16:29:55]

Acknowledged. I thought it was safe to change this because we don't yet have a
stable release with this change and the one before that. We only look at stable
metrics. Please let me know if you still need me to keep the same numbers.

[sebsg, 2017/05/05 16:46:31]

Oh I forgot you changed the whole histogram name from CardUploadDecisionExpanded
to CardUploadDecisionMetric. Normally I would still advocate to keep it
consistent in case you want to analyze the old data, but the old data is pretty
useless since it recorded only the first abort reason. 

So I think it's fine :)

-  <int value="2" label="Upload not offered, no address available"/>
-  <int value="3" label="Upload not offered, no name available"/>
-  <int value="4"
+  <int value="1" label="CVC field not detected"/>
+  <int value="2" label="CVC value not filled in detected CVC field"/>
+  <int value="3" label="Invalid CVC value filled in detected CVC field"/>
+  <int value="4" label="Upload not offered, no address available"/>
+  <int value="5" label="Upload not offered, no name available"/>
+  <int value="6"
       label="Upload not offered, addresses had conflicting zip codes"/>
-  <int value="5" label="Upload not offered, no zip code available"/>
-  <int value="6" label="Upload not offered, get upload details RPC failed"/>
-  <int value="7"
+  <int value="7" label="Upload not offered, no zip code available"/>
+  <int value="8"
       label="Upload not offered, card and/or addresses had conflicting names"/>
-  <int value="8" label="Upload offered, no CVC detected"/>
-  <int value="9" label="Upload not offered"/>
+  <int value="9" label="Upload not offered, get upload details RPC failed"/>
 </enum>
 
 <enum name="AutofillCreditCardInfoBar" type="int">