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..6341f331e18b9c93844a370bacd4f38a82588d7b 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;
@@ -196,6 +196,14 @@ message OmniboxEventProto {
       HISTORY_KEYWORD = 5;        // A past page whose keyword contains the
                                   // input
       NAVSUGGEST = 6;             // A suggested URL
+                                  //
+                                  // result_subtype_identifier is currently used
+                                  // for contextual zero suggestions provided by
+                                  // the experimental servicei (note that not all

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

two separate typos in this line

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

Fixed.

+                                  // NAVSUUGGEST suggestions are contextual
+                                  // zero-suggest suggestions).

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

replace:
are contextual zero-suggest suggestions
->
come from the experimental service

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

Done.

+                                  // For subtype definitions, please contact
+                                  // gcomanici@chromium.org.
       SEARCH_WHAT_YOU_TYPED = 7;  // The input as a search query (with the
                                   // default engine)
       SEARCH_HISTORY = 8;         // A past search (with the default engine)
@@ -253,6 +261,12 @@ message OmniboxEventProto {
 
     // Whether this item is disabled in the UI (not clickable).
     optional bool is_disabled = 6;
+
+    // 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. See enum ResultType above for more details.
+    optional int32 result_subtype_identifier = 7;
   }
   repeated Suggestion suggestion = 9;