Add a histogram for omnibox answer suggestion types.

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 60530d1d4d3e5fafa88a9623db742098c9a71c52..48c731f21eaccb5b98c4e4a05e7d1b4c185c1ce6 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -43189,6 +43189,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Omnibox.AnswerParseType" enum="SuggestionAnswerType">
+  <owner>jdonnelly@chromium.org</owner>
+  <summary>
+    The number of times each omnibox suggestion answer type (e.g., weather,
+    sports score) was received and parsed successfully. Can be normalized with
+    Omnibox.AnswerParseSuccess.

[Mark P, 2017/03/02 23:28:48]

For the follow-up changelist:
Normalizing by Omnibox.AnswerParseSuccess is unnecessary.  You can normalize by
the total number of items emitted to this histogram.

What I want to know was whether you were curious about a different normalization
factor ("e.g., against the total number of responses received and parsed
successfully"); see my original comment.
On 2017/03/02 21:21:25, Justin Donnelly wrote:
You're right; you were missing something. :-P

[Justin Donnelly, 2017/03/03 00:39:32]

Hmm, I think I'm still missing it. Based on the logging code in
search_suggestion_parser.cc the total number of items emitted to this histogram
should be the same thing as the number of responses parsed successfully. But if
it's not, why isn't Omnibox.AnswerParseSuccess that value? Is it because it's a
binary histogram (success/failure)? Like it would need to be a separate
non-histogram metric?

[Mark P, 2017/03/03 04:53:19]

Do we have a histogram for total number of responses parsed successfully?  As
far as I see, we only have a histogram for total number of answers suggestions
parsed successfully.

+  </summary>
+</histogram>
+
 <histogram name="Omnibox.CharTypedToRepaintLatency" units="ms">
   <owner>asvitkine@chromium.org</owner>
   <owner>mpearson@chromium.org</owner>
@@ -109780,6 +109789,19 @@ from previous Chrome versions.
   <int value="2" label="Load failed"/>
 </enum>
 
+<enum name="SuggestionAnswerType" type="int">
+  <summary>Type of Answer shown in omnibox suggestion list.</summary>
+  <int value="1" label="Dictionary"/>
+  <int value="2" label="Finance"/>
+  <int value="3" label="Knowledge graph"/>
+  <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"/>
+</enum>
+
 <enum name="SuggestionsResponseState" type="int">
   <int value="0" label="Empty response received from the server."/>
   <int value="1" label="Invalid response received from the server."/>