Identify unlaunched answer types in the answer types metric.

We're currently seeing some answers whose type doesn't match the list of
launched types. It would be helpful to see those in the timeline view.
The unknown values we're seeing are currently all 0 but I've included
the other known but unlaunched types in case they get erroneously (or
correctly) delivered in the future.

Bug: 
Change-Id: I9627675320d866c4cb4e8f44e90ed03ea45a897f
Reviewed-on: https://chromium-review.googlesource.com/587150
Commit-Queue: Justin Donnelly <jdonnelly@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#490818}

tools/metrics/histograms/enums.xml

@@ -36053,17 +36053,27 @@ from previous Chrome versions.
   <int value="2" label="Load failed"/>
 </enum>
 
+<!--
+These values are based on the server-side type AnswerTriggererKey. Note that not
+all of the types are launched in Chrome but if they're sent erroneously, it
+would be helpful to identify which type is being sent.
+-->
+
 <enum name="SuggestionAnswerType">
   <summary>Type of Answer shown in omnibox suggestion list.</summary>
+  <int value="0" label="Invalid (unknown type)"/>
   <int value="1" label="Dictionary"/>
   <int value="2" label="Finance"/>
   <int value="3" label="Knowledge graph"/>
+  <int value="4" label="Local"/>
   <int value="5" label="Sports"/>
   <int value="6" label="Sunrise"/>
   <int value="7" label="Translation"/>
   <int value="8" label="Weather"/>
   <int value="9" label="When is"/>
   <int value="10" label="Currency"/>
+  <int value="11" label="Local time"/>
+  <int value="12" label="Play install"/>
 </enum>
 
 <enum name="SuggestionsResponseState">