Add a new entry to omnibox_event.proto to log specific type of contextual suggestions

components/metrics/proto/omnibox_event.proto

Index: components/metrics/proto/omnibox_event.proto
diff --git a/components/metrics/proto/omnibox_event.proto b/components/metrics/proto/omnibox_event.proto
index 0410d6cc0edfd97b55f6d4b7dec11a15de84dcee..5b9e9af368e523038592da5689bbbc70e995f7d1 100644
--- a/components/metrics/proto/omnibox_event.proto
+++ b/components/metrics/proto/omnibox_event.proto
@@ -177,7 +177,7 @@ message OmniboxEventProto {
   }
 
   // The result set displayed on the completion popup
-  // Next tag: 7
+  // Next tag: 8
   message Suggestion {
     // Where does this result come from?
     optional ProviderType provider = 1;
@@ -253,6 +253,10 @@ message OmniboxEventProto {
 
     // Whether this item is disabled in the UI (not clickable).
     optional bool is_disabled = 6;
+
+    // This is an integer that is used to identify the type of a contextual
+    // suggestion provided through zero-suggest.

[Mark P, 2017/03/20 21:51:43]

Please use more generic language, because we want want to use this outside the
context of contextual suggestions / zero-suggest.  Perhaps, something like
// Used to identify the specific source / type of suggestion for suggestions
provided by the suggest server.  For meaning of individual values, see the
server-side enum.

[gcomanici, 2017/03/21 19:23:48]

Done.

+    optional int32 specific_type_identifier = 7;
   }
   repeated Suggestion suggestion = 9;