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

components/omnibox/browser/autocomplete_match.h

Index: components/omnibox/browser/autocomplete_match.h
diff --git a/components/omnibox/browser/autocomplete_match.h b/components/omnibox/browser/autocomplete_match.h
index 9ab496c7dc665b0f6ba3e7c7b95271b882cc1e00..f34032e5599b91dbabd0b65955e35a1c34aad089 100644
--- a/components/omnibox/browser/autocomplete_match.h
+++ b/components/omnibox/browser/autocomplete_match.h
@@ -367,6 +367,11 @@ struct AutocompleteMatch {
   // Type of this match.
   Type type;
 
+  // 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.

[Mark P, 2017/03/21 19:54:25]

nit: add
Only used for logging.
Please also explicit identify a value as being "unset".  0 is fine.  Whatever
you pick, you need to comment it.

[gcomanici, 2017/03/22 02:39:03]

Done.

+  int specific_type_identifier = 0;
+
   // Set with a keyword provider match if this match can show a keyword hint.
   // For example, if this is a SearchProvider match for "www.amazon.com",
   // |associated_keyword| could be a KeywordProvider match for "amazon.com".