Replace ResultProvider with 'aboutToComputeResult'.

pkg/analyzer/test/generated/engine_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.test.generated.engine_test;
 
 import 'dart:async';
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/source/embedder.dart';
@@ skipping 330 matching lines @@
     return null;
   }
 
   @override
   List<WorkManager> get workManagers {
     fail("Unexpected invocation of workManagers");
     return null;
   }
 
   @override
+  bool aboutToComputeResult(CacheEntry entry, ResultDescriptor result) {
+    fail("Unexpected invocation of aboutToComputeResult");
+    return false;
+  }
+
+  @override
   void addListener(AnalysisListener listener) {
     fail("Unexpected invocation of addListener");
   }
 
   @override
   void applyAnalysisDelta(AnalysisDelta delta) {
     fail("Unexpected invocation of applyAnalysisDelta");
   }
 
   @override
@@ skipping 306 matching lines @@
   bool validateCacheConsistency() {
     fail("Unexpected invocation of validateCacheConsistency");
     return false;
   }
 
   @override
   void visitContentCache(ContentCacheVisitor visitor) {
     fail("Unexpected invocation of visitContentCache");
   }
 }