Fetch federated PSL-matches from the password store.

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 efdf0cbeee68325f1e3af8b63e4698ed970e899e..1f8ca93ebb5c822a1ed23363e7b52a70ff23032b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -44581,8 +44581,11 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <owner>yfriedman@chromium.org</owner>
   <summary>
     Breakdown on trigger rate of providing a password form autofill entry based
-    on matching stored information using the public suffix list for possible
-    matches.
+    on matching stored information using the public suffix list (PSL) for
+    possible matches. In addition, this metric also counts cases where a
+    existing federated entry was successfully matched via PSL. For example, this
+    includes cases where an existing federated credential for
+    https://example.com was used for https://subdomain.example.com.
   </summary>
 </histogram>
 
@@ -99835,6 +99838,7 @@ value.
   <int value="0" label="Matching not used"/>
   <int value="1" label="No match"/>
   <int value="2" label="Match"/>
+  <int value="3" label="Federated match"/>

[Ilya Sherman, 2017/01/19 02:24:27]

Ah, I see, you are adding a bucket.  This change makes more sense now =)

 </enum>
 
 <enum name="PasswordManagerShowEmptyUsername" type="int">