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

components/metrics/proto/omnibox_event.proto

 // 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.
 //
 // Stores information about an omnibox interaction.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 option java_outer_classname = "OmniboxEventProtos";
@@ skipping 159 matching lines @@
     ON_DEVICE = 12;
     // This enum value is currently only used by Android GSA. It represents
     // a suggestion powered by a Chrome content provider.
     ON_DEVICE_CHROME = 13;
     CLIPBOARD_URL = 14;    // Suggestion coming from clipboard (iOS only).
     PHYSICAL_WEB = 15;     // Suggestions triggered by URLs broadcast by nearby
                            // devices (iOS and Android).
   }
 
   // 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;
 
     // What kind of result this is.
     // This corresponds to the AutocompleteMatch::Type enumeration in
     // components/omnibox/autocomplete_match.h (except for Android
     // GSA result types).
     enum ResultType {
       UNKNOWN_RESULT_TYPE = 0;    // Unknown type (should not reach here)
@@ skipping 55 matching lines @@
     // Only set for some providers and result_types.  At the time of
     // writing this comment, it is only set for HistoryURL and
     // HistoryQuickProvider matches.
     optional int32 typed_count = 5;
 
     // Whether this item is starred (bookmarked) or not.
     optional bool is_starred = 4 [deprecated=true];
 
     // 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;
 
   // A data structure that holds per-provider information, general information
   // not associated with a particular result.
   // Next tag: 6
   message ProviderInfo {
     // Which provider generated this ProviderInfo entry.
     optional ProviderType provider = 1;
 
@@ skipping 21 matching lines @@
     // The number of times this provider returned a non-zero number of
     // suggestions during this omnibox session.
     // Note that each provider may define a session differently for its
     // purposes.
     optional int32 times_returned_results_in_session = 5;
   }
   // A list of diagnostic information about each provider.  Providers
   // will appear at most once in this list.
   repeated ProviderInfo provider_info = 12;
 }