Separate the create and start phases in DelayedTaskManager.

base/task_scheduler/delayed_task_manager_unittest.cc

Index: base/task_scheduler/delayed_task_manager_unittest.cc
diff --git a/base/task_scheduler/delayed_task_manager_unittest.cc b/base/task_scheduler/delayed_task_manager_unittest.cc
index 8e6061d9c6b61d83985af9085ca74ca68e23b061..ce8cc0ea1f7f566c1fabd9f2dd77a808fdc59c4c 100644
--- a/base/task_scheduler/delayed_task_manager_unittest.cc
+++ b/base/task_scheduler/delayed_task_manager_unittest.cc
@@ -42,8 +42,7 @@ class MockTaskTarget {
 class TaskSchedulerDelayedTaskManagerTest : public testing::Test {
  public:
   TaskSchedulerDelayedTaskManagerTest()
-      : service_thread_task_runner_(new TestMockTimeTaskRunner),
-        delayed_task_manager_(service_thread_task_runner_) {}
+      : service_thread_task_runner_(new TestMockTimeTaskRunner) {}
   ~TaskSchedulerDelayedTaskManagerTest() override = default;
 
  protected:
@@ -56,8 +55,52 @@ class TaskSchedulerDelayedTaskManagerTest : public testing::Test {
 
 }  // namespace
 
-// Verify that a delayed task isn't forwarded before it is ripe for execution.
+// Verify that a delayed task isn't forwarded before Start().
+TEST_F(TaskSchedulerDelayedTaskManagerTest, DelayedTaskDoesNotRunBeforeStart) {
+  auto task =
+      MakeUnique<Task>(FROM_HERE, Bind(&DoNothing), TaskTraits(), kLongDelay);
+
+  testing::StrictMock<MockTaskTarget> task_target;
+
+  // Send |task| to the DelayedTaskManager.
+  delayed_task_manager_.AddDelayedTask(
+      std::move(task),
+      Bind(&MockTaskTarget::PostTaskNowCallback, Unretained(&task_target)));

[gab, 2017/04/12 19:15:51]

BindOnce

[fdoray, 2017/04/19 15:37:55]

Done.

+
+  // Fast-forward time. Don't expect any forwarding to |task_target|.

[gab, 2017/04/12 19:15:51]

What ensures this? Shouldn't your task trigger a failure if ran?

Edit: Oh I see, StrictMock ensures this, that's subtle... hint at this in this
comment? (it's more obvious in following tests that are followed by EXPECT_CALL
statements but this test is hard to read)

[fdoray, 2017/04/19 15:37:55]

Done.

+  service_thread_task_runner_->FastForwardBy(kLongDelay);
+}
+
+// Verify that a delayed task added before Start() is forwarded when it is ripe
+// for execution and Start() is called.
+TEST_F(TaskSchedulerDelayedTaskManagerTest,
+       DelayedTaskPostedBeforeStartRunsAfterStart) {
+  auto task =
+      MakeUnique<Task>(FROM_HERE, Bind(&DoNothing), TaskTraits(), kLongDelay);
+  const Task* task_raw = task.get();
+
+  testing::StrictMock<MockTaskTarget> task_target;
+
+  // Send |task| to the DelayedTaskManager.
+  delayed_task_manager_.AddDelayedTask(
+      std::move(task),
+      Bind(&MockTaskTarget::PostTaskNowCallback, Unretained(&task_target)));
+
+  delayed_task_manager_.Start(service_thread_task_runner_);
+
+  // Run tasks on the service thread. Don't expect any forwarding to
+  // |task_target| since the task isn't ripe for execution.
+  service_thread_task_runner_->RunUntilIdle();
+
+  // Fast-forward time. Expect the task to be forwarded to |task_target|.
+  EXPECT_CALL(task_target, DoPostTaskNowCallback(task_raw));
+  service_thread_task_runner_->FastForwardBy(kLongDelay);
+}

[gab, 2017/04/12 19:15:51]

Also test that task that became ripe before start is executed upon Start()?

[fdoray, 2017/04/19 15:37:55]

Done.

+
+// Verify that a delayed task added after Start() isn't forwarded before it is
+// ripe for execution.
 TEST_F(TaskSchedulerDelayedTaskManagerTest, DelayedTaskDoesNotRunTooEarly) {
+  delayed_task_manager_.Start(service_thread_task_runner_);
   auto task =
       MakeUnique<Task>(FROM_HERE, Bind(&DoNothing), TaskTraits(), kLongDelay);
 
@@ -73,8 +116,10 @@ TEST_F(TaskSchedulerDelayedTaskManagerTest, DelayedTaskDoesNotRunTooEarly) {
   service_thread_task_runner_->RunUntilIdle();
 }
 
-// Verify that a delayed task is forwarded when it is ripe for execution.
+// Verify that a delayed task added after Start() is forwarded when it is ripe
+// for execution.
 TEST_F(TaskSchedulerDelayedTaskManagerTest, DelayedTaskRunsAfterDelay) {
+  delayed_task_manager_.Start(service_thread_task_runner_);
   auto task =
       MakeUnique<Task>(FROM_HERE, Bind(&DoNothing), TaskTraits(), kLongDelay);
   const Task* task_raw = task.get();
@@ -91,9 +136,10 @@ TEST_F(TaskSchedulerDelayedTaskManagerTest, DelayedTaskRunsAfterDelay) {
   service_thread_task_runner_->FastForwardBy(kLongDelay);
 }
 
-// Verify that multiple delayed tasks are forwarded when they are ripe for
-// execution.
+// Verify that multiple delayed tasks added after Start() are forwarded when
+// they are ripe for execution.
 TEST_F(TaskSchedulerDelayedTaskManagerTest, DelayedTasksRunAfterDelay) {
+  delayed_task_manager_.Start(service_thread_task_runner_);
   auto task_a = MakeUnique<Task>(FROM_HERE, Bind(&DoNothing), TaskTraits(),
                                  TimeDelta::FromHours(1));
   const Task* task_a_raw = task_a.get();