Mark ukm metrics which need semantic_type annotation.

Change-Id: I60c844d30fe3b7c01a8a42922b7633f830b8dda8
Reviewed-on: https://chromium-review.googlesource.com/602518Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Steven Holte <holte@chromium.org>
Cr-Commit-Position: refs/heads/master@{#492431}

tools/metrics/ukm/model.py

@@ -18,7 +18,10 @@ _LOWERCASE_NAME_FN = lambda n: n.attributes['name'].value.lower()
 
 _METRIC_TYPE =  models.ObjectNodeType(
     'metric',
-    attributes=[('name', unicode)],
+    attributes=[
+      ('name', unicode),
+      ('semantic_type', unicode),
+    ],
     children=[
         models.ChildType('obsolete', _OBSOLETE_TYPE, False),
         models.ChildType('owners', _OWNER_TYPE, True),

tools/metrics/ukm/ukm.xml

@@ -1046,8 +1046,8 @@ be describing additional metrics about the same event.
   <metric name="IgnoreCount"/>
   <metric name="RankerResponse"/>
   <metric name="RankerVersion"/>
-  <metric name="SourceLanguage"/>
-  <metric name="TargetLanguage"/>
+  <metric name="SourceLanguage" semantic_type="ST_DEMOGRAPHIC_INFO"/>
+  <metric name="TargetLanguage" semantic_type="ST_DEMOGRAPHIC_INFO"/>
 </event>
 
 <event name="CPUUsageMeasurement">