Generate constants in server as we do in plugin

pkg/analysis_server/lib/src/search/search_domain.dart

Index: pkg/analysis_server/lib/src/search/search_domain.dart
diff --git a/pkg/analysis_server/lib/src/search/search_domain.dart b/pkg/analysis_server/lib/src/search/search_domain.dart
index ebb32456c6fc05ee649cbf3e595b40304286795b..47778a81690ca8ba937ae4380b8d9ead1e4f4d99 100644
--- a/pkg/analysis_server/lib/src/search/search_domain.dart
+++ b/pkg/analysis_server/lib/src/search/search_domain.dart
@@ -4,8 +4,8 @@
 
 import 'dart:async';
 
+import 'package:analysis_server/protocol/protocol_constants.dart';
 import 'package:analysis_server/src/analysis_server.dart';
-import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol_server.dart' as protocol;
 import 'package:analysis_server/src/search/element_references.dart';
 import 'package:analysis_server/src/search/type_hierarchy.dart';
@@ -169,19 +169,19 @@ class SearchDomainHandler implements protocol.RequestHandler {
   protocol.Response handleRequest(protocol.Request request) {
     try {
       String requestName = request.method;
-      if (requestName == SEARCH_FIND_ELEMENT_REFERENCES) {
+      if (requestName == SEARCH_REQUEST_FIND_ELEMENT_REFERENCES) {
         findElementReferences(request);
         return protocol.Response.DELAYED_RESPONSE;
-      } else if (requestName == SEARCH_FIND_MEMBER_DECLARATIONS) {
+      } else if (requestName == SEARCH_REQUEST_FIND_MEMBER_DECLARATIONS) {
         findMemberDeclarations(request);
         return protocol.Response.DELAYED_RESPONSE;
-      } else if (requestName == SEARCH_FIND_MEMBER_REFERENCES) {
+      } else if (requestName == SEARCH_REQUEST_FIND_MEMBER_REFERENCES) {
         findMemberReferences(request);
         return protocol.Response.DELAYED_RESPONSE;
-      } else if (requestName == SEARCH_FIND_TOP_LEVEL_DECLARATIONS) {
+      } else if (requestName == SEARCH_REQUEST_FIND_TOP_LEVEL_DECLARATIONS) {
         findTopLevelDeclarations(request);
         return protocol.Response.DELAYED_RESPONSE;
-      } else if (requestName == SEARCH_GET_TYPE_HIERARCHY) {
+      } else if (requestName == SEARCH_REQUEST_GET_TYPE_HIERARCHY) {
         getTypeHierarchy(request);
         return protocol.Response.DELAYED_RESPONSE;
       }