Rework local benchmarks into benchmarks on the Flutter codebase.

pkg/analysis_server/benchmark/perf/benchmark_scenario.dart

 // Copyright (c) 2016, 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 server.performance.scenarios;
 
 import 'dart:async';
 import 'dart:io';
+import 'dart:math';
 
 import 'package:analysis_server/plugin/protocol/protocol.dart';
 import 'package:unittest/unittest.dart';
 
 import 'performance_tests.dart';
 
 void printBenchmarkResults(String id, String description, List<int> times) {
+  int minTime = times.fold(1 << 20, min);
   String now = new DateTime.now().toUtc().toIso8601String();
   print('$now ========== $id');
   print('times: $times');
+  print('min_time: $minTime');
   print(description.trim());
   print('--------------------');
   print('');
   print('');
 }
 
 class BenchmarkScenario extends AbstractTimingTest {
   /**
    * Init.
    *  - Start Analysis Server.
@@ skipping 149 matching lines @@
     await shutdown();
     return times;
   }
 
   /**
    * Compute updated content of the [file] as described by [desc], add overlay
    * for the [file], and return the updated content.
    */
   Future<String> _applyFileChange(String file, FileChange desc) async {
     String originalContent = _getFileContent(file);
-    int offset = _indexOfEnd(file, originalContent, desc.afterStr);
-    offset -= desc.afterStrBack;
-    String updatedContent = originalContent.substring(0, offset) +
-        desc.insertStr +
-        originalContent.substring(offset);
+    String updatedContent;
+    if (desc.afterStr != null) {
+      int offset = _indexOfEnd(file, originalContent, desc.afterStr);
+      offset -= desc.afterStrBack;
+      updatedContent = originalContent.substring(0, offset) +
+          desc.insertStr +
+          originalContent.substring(offset);
+    } else if (desc.replaceWhat != null) {
+      int offset = _indexOf(file, originalContent, desc.replaceWhat);
+      updatedContent = originalContent.substring(0, offset) +
+          desc.replaceWith +
+          originalContent.substring(offset + desc.replaceWhat.length);
+    }
     await sendAnalysisUpdateContent(
         {file: new AddContentOverlay(updatedContent)});
     return updatedContent;
   }
 
   Future<Duration> _measureCompletionTime(String file, int offset) async {
     Stopwatch stopwatch = new Stopwatch();
     stopwatch.start();
     Completer<Duration> completer = new Completer<Duration>();
     var completionSubscription = onCompletionResults.listen((_) {
@@ skipping 69 matching lines @@
    */
   static int _indexOfEnd(String file, String where, String what) {
     return _indexOf(file, where, what) + what.length;
   }
 }
 
 class FileChange {
   final String afterStr;
   final int afterStrBack;
   final String insertStr;
+  final String replaceWhat;
+  final String replaceWith;
 
-  FileChange({this.afterStr, this.afterStrBack: 0, this.insertStr}) {
-    expect(afterStr, isNotNull, reason: 'afterStr');
-    expect(insertStr, isNotNull, reason: 'insertStr');
+  FileChange({this.afterStr, this.afterStrBack: 0, this.insertStr, this.replaceWhat, this.replaceWith}) {
+    if (afterStr != null) {
+      expect(insertStr, isNotNull, reason: 'insertStr');
+    } else if (replaceWhat != null) {
+      expect(replaceWith, isNotNull, reason: 'replaceWith');
+    }
   }
 }