Push add*Edit helpers into SourceChange.

pkg/analysis_server/lib/src/services/refactoring/extract_local.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 services.src.refactoring.extract_local;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart' hide Element;
 import 'package:analysis_server/src/services/correction/name_suggestion.dart';
@@ skipping 105 matching lines @@
     } else {
       occurrences = [selectionRange];
     }
     // If the whole expression of a statement is selected, like '1 + 2',
     // then convert it into a variable declaration statement.
     if (wholeStatementExpression && occurrences.length == 1) {
       String keyword = _declarationKeyword;
       String declarationSource = '$keyword $name = ';
       SourceEdit edit =
           new SourceEdit(singleExpression.offset, 0, declarationSource);
-      addElementSourceChange(change, unitElement, edit);
+      change.addElementEdit(unitElement, edit);
       return new Future.value(change);
     }
     // add variable declaration
     {
       String declarationSource;
       if (stringLiteralPart != null) {
         declarationSource = "var $name = '$stringLiteralPart';";
       } else {
         String keyword = _declarationKeyword;
         String initializerSource = utils.getRangeText(selectionRange);
@@ skipping 15 matching lines @@
             target_ = commonParent.getAncestor((node) => node is Statement);
           }
         }
       }
       AstNode target = target_;
       // insert variable declaration
       if (target is Statement) {
         String prefix = utils.getNodePrefix(target);
         SourceEdit edit =
             new SourceEdit(target.offset, 0, declarationSource + eol + prefix);
-        addElementSourceChange(change, unitElement, edit);
+        change.addElementEdit(unitElement, edit);
       } else if (target is ExpressionFunctionBody) {
         String prefix = utils.getNodePrefix(target.parent);
         String indent = utils.getIndent(1);
         String declStatement = prefix + indent + declarationSource + eol;
         String exprStatement = prefix + indent + 'return ';
         Expression expr = target.expression;
-        addElementSourceChange(
-            change,
+        change.addElementEdit(
             unitElement,
             new SourceEdit(
                 target.offset,
                 expr.offset - target.offset,
                 '{' + eol + declStatement + exprStatement));
-        addElementSourceChange(
-            change,
+        change.addElementEdit(
             unitElement,
             new SourceEdit(expr.end, 0, ';' + eol + prefix + '}'));
       }
     }
     // prepare replacement
     String occurrenceReplacement = name;
     if (stringLiteralPart != null) {
       occurrenceReplacement = "\${$name}";
     }
     // replace occurrences with variable reference
     for (SourceRange range in occurrences) {
       SourceEdit edit = new SourceEdit.range(range, occurrenceReplacement);
-      addElementSourceChange(change, unitElement, edit);
+      change.addElementEdit(unitElement, edit);
     }
     // done
     return new Future.value(change);
   }
 
   @override
   bool requiresPreview() => false;
 
   /**
    * Checks if [selectionRange] selects [Expression] which can be extracted, and
@@ skipping 361 matching lines @@
       Token startToken = nodeTokens[startTokenIndex];
       Token endToken = nodeTokens[endTokenIndex];
       // add occurrence range
       int occuStart = nodeOffset + startToken.offset;
       int occuEnd = nodeOffset + endToken.end;
       SourceRange occuRange = rangeStartEnd(occuStart, occuEnd);
       _addOccurrence(occuRange);
     }
   }
 }