TaskScheduler: Don't use a callback to post a task from TaskTracker.

base/task_scheduler/scheduler_worker_thread_unittest.cc

Index: base/task_scheduler/scheduler_worker_thread_unittest.cc
diff --git a/base/task_scheduler/scheduler_worker_thread_unittest.cc b/base/task_scheduler/scheduler_worker_thread_unittest.cc
index 279638859405eaac6b0569c8f8fabaaf9e1aaece..63e1cf6e6d69543cdff118b3a7708d58f74f1805 100644
--- a/base/task_scheduler/scheduler_worker_thread_unittest.cc
+++ b/base/task_scheduler/scheduler_worker_thread_unittest.cc
@@ -130,12 +130,12 @@ class TaskSchedulerWorkerThreadTest : public testing::Test,
 
     // Create a Sequence that contains one Task.
     scoped_refptr<Sequence> sequence(new Sequence);
-    task_tracker_.PostTask(
-        Bind(IgnoreResult(&Sequence::PushTask), Unretained(sequence.get())),
-        WrapUnique(new Task(
-            FROM_HERE, Bind(&TaskSchedulerWorkerThreadTest::RunTaskCallback,
-                            Unretained(this)),
-            TaskTraits())));
+    std::unique_ptr<Task> task(new Task(
+        FROM_HERE,
+        Bind(&TaskSchedulerWorkerThreadTest::RunTaskCallback, Unretained(this)),
+        TaskTraits()));
+    EXPECT_TRUE(task_tracker_.WillPostTask(task.get()));
+    sequence->PushTask(std::move(task));
 
     {
       // Add the Sequence to the vector of created Sequences.