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

components/omnibox/browser/autocomplete_match.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_MATCH_H_
 #define COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_MATCH_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 349 matching lines @@
   std::unique_ptr<SuggestionAnswer> answer;
 
   // The transition type to use when the user opens this match.  By default
   // this is TYPED.  Providers whose matches do not look like URLs should set
   // it to GENERATED.
   ui::PageTransition transition;
 
   // Type of this match.
   Type type;
 
+  // Used to identify the specific source / type for suggestions by the
+  // suggest server. The meaning of individual values is determined by the
+  // provider of each suggestion type and is different for every suggestion
+  // type. Contact service providers for more details.

[Mark P, 2017/03/31 20:50:25]

To correct my earlier suggestion, perhaps instead of the last two sentences,
say,
See |result_subtype_identifier| in omnibox.event.proto for more details.

[gcomanici, 2017/04/01 16:01:52]

Done.

[Mark P, 2017/04/01 21:08:03]

In a trivial follow-up changelist, can you please revise this to say
result_subtype_identifier as I suggested?  You mentioned result_type_identifier,
which is not the name of the field in omnibox_event.proto.

ditto other file

+  // The identifier 0 is reserved for cases where this specific type is unset.
+  int subtype_identifier;
+
   // 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".
   //
   // When this is set, the popup will show a ">" symbol at the right edge of the
   // line for this match, and tab/shift-tab will toggle in and out of keyword
   // mode without disturbing the rest of the popup.  See also
   // OmniboxPopupModel::SetSelectedLineState().
   std::unique_ptr<AutocompleteMatch> associated_keyword;
 
@@ skipping 39 matching lines @@
       const base::string16& text,
       const ACMatchClassifications& classifications) const;
 #endif
 };
 
 typedef AutocompleteMatch::ACMatchClassification ACMatchClassification;
 typedef std::vector<ACMatchClassification> ACMatchClassifications;
 typedef std::vector<AutocompleteMatch> ACMatches;
 
 #endif  // COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_MATCH_H_