TaskScheduler: Add TaskRunnerHandle support to TaskScheduler tasks

base/task_scheduler/test_task_factory.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_TASK_SCHEDULER_TEST_TASK_FACTORY_H_
 #define BASE_TASK_SCHEDULER_TEST_TASK_FACTORY_H_
 
 #include <stddef.h>
 
 #include <unordered_set>
@@ skipping 11 matching lines @@
 
 class WaitableEvent;
 
 namespace internal {
 namespace test {
 
 // A TestTaskFactory posts tasks to a TaskRunner and verifies that they run as
 // expected. Generates a test failure when:
 // - The RunsTasksOnCurrentThread() method of the TaskRunner returns false on a
 //   thread on which a Task is run.
+// - The TaskRunnerHandles set in the context of the task don't match what's
+//   expected for the tested ExecutionMode.
 // - The ExecutionMode of the TaskRunner is SEQUENCED or SINGLE_THREADED and
 //   Tasks don't run in posting order.
-// - The ExecutionMode of the TaskRunner is SINGLE_THREADED and Tasks don't
-//   run on the same thread.
+// - The ExecutionMode of the TaskRunner is SINGLE_THREADED and Tasks don't run
+//   on the same thread.
 // - A Task runs more than once.
 class TestTaskFactory {
  public:
   enum class PostNestedTask {
     YES,
     NO,
   };
 
   // Constructs a TestTaskFactory that posts tasks to |task_runner|.
   // |execution_mode| is the ExecutionMode of |task_runner|.
@@ skipping 44 matching lines @@
   ThreadCheckerImpl thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(TestTaskFactory);
 };
 
 }  // namespace test
 }  // namespace internal
 }  // namespace base
 
 #endif  // BASE_TASK_SCHEDULER_TEST_TASK_FACTORY_H_