TaskScheduler: Adjust shutdown behavior of delayed tasks.

With this CL, the shutdown behavior of a task posted with a delay to a
BLOCK_SHUTDOWN TaskRunner is automatically adjusted to SKIP_ON_SHUTDOWN.
This ensures that a delayed task never blocks shutdown before being
scheduled. This matches the behavior of SequencedWorkerPool.

TBR=danakj@chromium.org
BUG=553459

Review-Url: https://codereview.chromium.org/2383193002
Cr-Commit-Position: refs/heads/master@{#422541}


CrOS-Libchrome-Original-Commit: ad44b092b755176fc0f57ad0330efa2944d22a94
diff --git a/base/task_scheduler/task_unittest.cc b/base/task_scheduler/task_unittest.cc
new file mode 100644
index 0000000..e6a2c51
--- /dev/null
+++ b/base/task_scheduler/task_unittest.cc
@@ -0,0 +1,67 @@
+// 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.
+
+#include "base/task_scheduler/task.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/task_scheduler/task_traits.h"
+#include "base/time/time.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace internal {
+
+// Verify that the shutdown behavior of a BLOCK_SHUTDOWN delayed task is
+// adjusted to SKIP_ON_SHUTDOWN. The shutown behavior of other delayed tasks
+// should not change.
+TEST(TaskSchedulerTaskTest, ShutdownBehaviorChangeWithDelay) {
+  Task continue_on_shutdown(FROM_HERE, Bind(&DoNothing),
+                            TaskTraits().WithShutdownBehavior(
+                                TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN),
+                            TimeDelta::FromSeconds(1));
+  EXPECT_EQ(TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN,
+            continue_on_shutdown.traits.shutdown_behavior());
+
+  Task skip_on_shutdown(
+      FROM_HERE, Bind(&DoNothing),
+      TaskTraits().WithShutdownBehavior(TaskShutdownBehavior::SKIP_ON_SHUTDOWN),
+      TimeDelta::FromSeconds(1));
+  EXPECT_EQ(TaskShutdownBehavior::SKIP_ON_SHUTDOWN,
+            skip_on_shutdown.traits.shutdown_behavior());
+
+  Task block_shutdown(
+      FROM_HERE, Bind(&DoNothing),
+      TaskTraits().WithShutdownBehavior(TaskShutdownBehavior::BLOCK_SHUTDOWN),
+      TimeDelta::FromSeconds(1));
+  EXPECT_EQ(TaskShutdownBehavior::SKIP_ON_SHUTDOWN,
+            block_shutdown.traits.shutdown_behavior());
+}
+
+// Verify that the shutdown behavior of undelayed tasks is not adjusted.
+TEST(TaskSchedulerTaskTest, NoShutdownBehaviorChangeNoDelay) {
+  Task continue_on_shutdown(FROM_HERE, Bind(&DoNothing),
+                            TaskTraits().WithShutdownBehavior(
+                                TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN),
+                            TimeDelta());
+  EXPECT_EQ(TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN,
+            continue_on_shutdown.traits.shutdown_behavior());
+
+  Task skip_on_shutdown(
+      FROM_HERE, Bind(&DoNothing),
+      TaskTraits().WithShutdownBehavior(TaskShutdownBehavior::SKIP_ON_SHUTDOWN),
+      TimeDelta());
+  EXPECT_EQ(TaskShutdownBehavior::SKIP_ON_SHUTDOWN,
+            skip_on_shutdown.traits.shutdown_behavior());
+
+  Task block_shutdown(
+      FROM_HERE, Bind(&DoNothing),
+      TaskTraits().WithShutdownBehavior(TaskShutdownBehavior::BLOCK_SHUTDOWN),
+      TimeDelta());
+  EXPECT_EQ(TaskShutdownBehavior::BLOCK_SHUTDOWN,
+            block_shutdown.traits.shutdown_behavior());
+}
+
+}  // namespace internal
+}  // namespace base