base: Let ThreadTaskRunnerHandle::Get() return NULL

base/thread_task_runner_handle_unittest.cc

+// Copyright 2015 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.
+
+#include "base/thread_task_runner_handle.h"
+
+#include "base/test/test_simple_task_runner.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+TEST(ThreadTaskRunnerHandleTest, NullRunner) {
+  EXPECT_FALSE(ThreadTaskRunnerHandle::IsSet());
+  EXPECT_EQ(nullptr, ThreadTaskRunnerHandle::Get());
+  scoped_refptr<TestSimpleTaskRunner> task_runner(new TestSimpleTaskRunner);
+  ThreadTaskRunnerHandle handle(task_runner);
+  EXPECT_TRUE(ThreadTaskRunnerHandle::IsSet());
+  EXPECT_EQ(task_runner, ThreadTaskRunnerHandle::Get());
+}
+
+}  // namespace base