Make pkg/stack_trace use stack chains.

pkg/scheduled_test/lib/src/schedule_error.dart

 // Copyright (c) 2013, 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 schedule_error;
 
-import 'dart:async';
-
 import 'package:stack_trace/stack_trace.dart';
 
 import 'schedule.dart';
 import 'task.dart';
 import 'utils.dart';
 
 /// A wrapper for errors that occur during a scheduled test.
 class ScheduleError {
   /// The wrapped error.
   final error;
 
   /// The stack trace that was attached to the error. Can be `null`.
-  final stackTrace;
+  final StackTrace stackTrace;
 
   /// The schedule during which this error occurred.
   final Schedule schedule;
 
   /// The task that was running when this error occurred. This may be `null` if
   /// there was no such task.
   final Task task;
 
   /// The task queue that was running when this error occured. This may be
   /// `null` if there was no such queue.
@@ skipping 14 matching lines @@
   factory ScheduleError.from(Schedule schedule, error,
                              {StackTrace stackTrace}) {
     if (error is ScheduleError) return error;
 
     if (stackTrace == null && error is Error) {
       // Overwrite the explicit stack trace, because it probably came from a
       // rethrow in the first place.
       stackTrace = error.stackTrace;
     }
 
-    if (stackTrace == null) stackTrace = new Trace.current();
+    if (stackTrace == null) stackTrace = new Chain.current();
     return new ScheduleError(schedule, error, stackTrace);
   }
 
-  // TODO(floitsch): restore StackTrace type when it has been integrated into
-  // the core libraries.
-  ScheduleError(Schedule schedule, error, var stackTrace)
-      : error = error,
-        stackTrace = stackTrace,
-        schedule = schedule,
+  ScheduleError(Schedule schedule, this.error, this.stackTrace)
+      : schedule = schedule,
         task = schedule.currentTask,
         queue = schedule.currentQueue,
         pendingCallbacks = schedule.currentQueue == null ? <PendingCallback>[]
             : schedule.currentQueue.pendingCallbacks.toList(),
         _stateWhenDetected = schedule.state;
 
   bool operator ==(other) => other is ScheduleError && task == other.task &&
       queue == other.queue && _stateWhenDetected == other._stateWhenDetected &&
       error == other.error && stackTrace == other.stackTrace;
 
   String toString() {
     var result = new StringBuffer();
 
     var errorString = error.toString();
     if (errorString.contains("\n")) {
       result.write('ScheduleError:\n');
       result.write(prefixLines(errorString.trim()));
       result.write("\n\n");
     } else {
       result.write('ScheduleError: "$errorString"\n');
     }
 
     if (stackTrace != null) {
-      result.write('Stack trace:\n');
+      result.write('Stack chain:\n');
       result.write(prefixLines(terseTraceString(stackTrace)));
       result.write("\n\n");
     }
 
     if (task != null) {
       result.write('Error detected during task in queue "$queue":\n');
       result.write(task.generateTree());
     } else if (_stateWhenDetected == ScheduleState.DONE) {
       result.write('Error detected after all tasks in the schedule had '
           'finished.');
     } else if (_stateWhenDetected == ScheduleState.RUNNING) {
       result.write('Error detected when waiting for out-of-band callbacks in '
           'queue "$queue".');
     } else { // _stateWhenDetected == ScheduleState.SET_UP
       result.write('Error detected before the schedule started running.');
     }
 
     if (!pendingCallbacks.isEmpty) {
       result.write("\n\n");
       result.writeln("Pending out-of-band callbacks:");
       for (var callback in pendingCallbacks) {
         result.writeln(prefixLines(callback.toString(), firstPrefix: "* "));
       }
     }
 
     return result.toString().trim();
   }
 }