Issue 22157. Cancel a pending refactoring request on receiving a new one.

pkg/analysis_server/lib/src/protocol.dart

Index: pkg/analysis_server/lib/src/protocol.dart
diff --git a/pkg/analysis_server/lib/src/protocol.dart b/pkg/analysis_server/lib/src/protocol.dart
index 1161df17765290fdd924ac11adfc321057659f06..dfa810cdb1deb06f8617cc37ca9097667b1bb150 100644
--- a/pkg/analysis_server/lib/src/protocol.dart
+++ b/pkg/analysis_server/lib/src/protocol.dart
@@ -810,6 +810,17 @@ class Response {
 
   /**
    * Initialize a newly created instance to represent the
+   * REFACTORING_REQUEST_CANCELLED error condition.
+   */
+  Response.refactoringRequestCancelled(Request request)
+      : this(
+          request.id,
+          error: new RequestError(
+              RequestErrorCode.REFACTORING_REQUEST_CANCELLED,
+              'The `edit.getRefactoring` request was cancelled.'));
+
+  /**
+   * Initialize a newly created instance to represent the
    * SORT_MEMBERS_PARSE_ERRORS error condition.
    */
   Response.sortMembersParseErrors(Request request, int numErrors)