Remove default case from autofill_metrics.cc::GetFieldTypeGroupMetric

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 d45b24a4965157ae0c0ac83d6e67c0a1ee30ca2f..134e7f5b1d87dfa191a273969cf8cec8338d9140 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -18644,6 +18644,9 @@ other types of suffix sets.
   <int value="42" label="Credit card: date, Unknown"/>
   <int value="43" label="Credit card: date, Match"/>
   <int value="44" label="Credit card: date, Mismatch"/>
+  <int value="45" label="Password, Unknown"/>

[Jim Blackler, 2013/11/14 17:33:15]

Is it possible this should read '48' and not '45'?

The end of this list now reads..

  <int value="36" label="Credit card: name, Unknown"/>
  <int value="37" label="Credit card: name, Match"/>
  <int value="38" label="Credit card: name, Mismatch"/>
  <int value="39" label="Credit card: number, Unknown"/>
  <int value="40" label="Credit card: number, Match"/>
  <int value="41" label="Credit card: number, Mismatch"/>
  <int value="42" label="Credit card: date, Unknown"/>
  <int value="43" label="Credit card: date, Match"/>
  <int value="44" label="Credit card: date, Mismatch"/>
  <int value="45" label="Password, Unknown"/>
  <int value="46" label="Password, Match"/>
  <int value="47" label="Password, Mismatch"/>

.. ie. with nothing between "Credit card: date" and "Password"

But enum FieldTypeGroupForMetrics reads...

enum FieldTypeGroupForMetrics {
//..
  CREDIT_CARD_NAME,
  CREDIT_CARD_NUMBER,
  CREDIT_CARD_DATE,
  CREDIT_CARD_TYPE,
  PASSWORD,
  NUM_FIELD_TYPE_GROUPS_FOR_METRICS
};

So it looks like we're missing three numbers for 'Credit card: Type" which
should occupy the slots 45 to 47 and the Password metrics should occupy slots 48
to 51.  Since I believe FieldTypeGroupForMetrics::CREDIT_CARD_TYPE = 15 (*3 =
45) and FieldTypeGroupForMetrics::PASSWORD = 16 (*3 = 48).

This would explain the mystery '48' type we are seeing on iOS metrics reports,
see bug https://code.google.com/p/chromium/issues/detail?id=317749

[Ilya Sherman, 2013/11/15 06:35:56]

Yes, I believe you are correct.  Thanks for catching that!

+  <int value="46" label="Password, Match"/>
+  <int value="47" label="Password, Mismatch"/>
 </enum>
 
 <enum name="AutofillUserHappiness" type="int">