Change behaivor to decide whether a search engine should be shown in the default list

components/sync/protocol/search_engine_specifics.proto

Index: components/sync/protocol/search_engine_specifics.proto
diff --git a/components/sync/protocol/search_engine_specifics.proto b/components/sync/protocol/search_engine_specifics.proto
index e9f3cd9322795374a6a11e6b4d1e8cda94c47145..03a3e07f8066bfa93068c68453600909a4cab7db 100644
--- a/components/sync/protocol/search_engine_specifics.proto
+++ b/components/sync/protocol/search_engine_specifics.proto
@@ -33,8 +33,9 @@ message SearchEngineSpecifics {
   optional int64 date_created = 7;
   // A list of supported input encodings.
   optional string input_encodings = 8;
-  // Whether this entry is shown in the list of default search engines or not.
-  optional bool show_in_default_list = 9;
+  // Obsolete field. This used to represent whether or not this entry is shown
+  // in the list of default search engines.
+  // optional bool deprecated_show_in_default_list = 9;
   // The parameterized URL that provides suggestions as the user types.
   optional string suggestions_url = 10;
   // The ID associated with the prepopulate data this search engine comes from.