Implement Shared SingleThreadTaskRunners in the Task Scheduler

base/task_scheduler/scheduler_single_thread_task_runner_manager_unittest.cc

Index: base/task_scheduler/scheduler_single_thread_task_runner_manager_unittest.cc
diff --git a/base/task_scheduler/scheduler_single_thread_task_runner_manager_unittest.cc b/base/task_scheduler/scheduler_single_thread_task_runner_manager_unittest.cc
index 4415f5fd808adbd83124cac4686b062d8549e649..4c6153f0af4f38359d6bbe7e7b69a37952bc270a 100644
--- a/base/task_scheduler/scheduler_single_thread_task_runner_manager_unittest.cc
+++ b/base/task_scheduler/scheduler_single_thread_task_runner_manager_unittest.cc
@@ -93,12 +93,14 @@ TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest, DifferentThreadsUsed) {
       single_thread_task_runner_manager_
           ->CreateSingleThreadTaskRunnerWithTraits(
               "A", ThreadPriority::NORMAL,
-              {TaskShutdownBehavior::BLOCK_SHUTDOWN});
+              {TaskShutdownBehavior::BLOCK_SHUTDOWN},
+              SingleThreadTaskRunnerThreadMode::DEDICATED);
   scoped_refptr<SingleThreadTaskRunner> task_runner_2 =
       single_thread_task_runner_manager_
           ->CreateSingleThreadTaskRunnerWithTraits(
               "B", ThreadPriority::NORMAL,
-              {TaskShutdownBehavior::BLOCK_SHUTDOWN});
+              {TaskShutdownBehavior::BLOCK_SHUTDOWN},
+              SingleThreadTaskRunnerThreadMode::DEDICATED);
 
   PlatformThreadRef thread_ref_1;
   task_runner_1->PostTask(FROM_HERE,
@@ -114,19 +116,103 @@ TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest, DifferentThreadsUsed) {
   EXPECT_NE(thread_ref_1, thread_ref_2);
 }
 
-TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest, PrioritySetCorrectly) {
+TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest, SameThreadUsed) {
+  scoped_refptr<SingleThreadTaskRunner> task_runner_1 =
+      single_thread_task_runner_manager_
+          ->CreateSingleThreadTaskRunnerWithTraits(
+              "A", ThreadPriority::NORMAL,
+              {TaskShutdownBehavior::BLOCK_SHUTDOWN},
+              SingleThreadTaskRunnerThreadMode::SHARED);
+  scoped_refptr<SingleThreadTaskRunner> task_runner_2 =
+      single_thread_task_runner_manager_
+          ->CreateSingleThreadTaskRunnerWithTraits(
+              "B", ThreadPriority::NORMAL,
+              {TaskShutdownBehavior::BLOCK_SHUTDOWN},
+              SingleThreadTaskRunnerThreadMode::SHARED);
+
+  PlatformThreadRef thread_ref_1;
+  task_runner_1->PostTask(FROM_HERE,
+                          BindOnce(&CaptureThreadRef, &thread_ref_1));
+  PlatformThreadRef thread_ref_2;
+  task_runner_2->PostTask(FROM_HERE,
+                          BindOnce(&CaptureThreadRef, &thread_ref_2));
+
+  task_tracker_.Shutdown();
+
+  ASSERT_FALSE(thread_ref_1.is_null());
+  ASSERT_FALSE(thread_ref_2.is_null());
+  EXPECT_EQ(thread_ref_1, thread_ref_2);
+}
+
+TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest,
+       RunsTasksOnCurrentThread) {
+  scoped_refptr<SingleThreadTaskRunner> task_runner_1 =
+      single_thread_task_runner_manager_
+          ->CreateSingleThreadTaskRunnerWithTraits(
+              "A", ThreadPriority::NORMAL,
+              {TaskShutdownBehavior::BLOCK_SHUTDOWN},
+              SingleThreadTaskRunnerThreadMode::DEDICATED);
+  scoped_refptr<SingleThreadTaskRunner> task_runner_2 =
+      single_thread_task_runner_manager_
+          ->CreateSingleThreadTaskRunnerWithTraits(
+              "B", ThreadPriority::NORMAL,
+              {TaskShutdownBehavior::BLOCK_SHUTDOWN},
+              SingleThreadTaskRunnerThreadMode::DEDICATED);
+
+  EXPECT_FALSE(task_runner_1->RunsTasksOnCurrentThread());
+  EXPECT_FALSE(task_runner_2->RunsTasksOnCurrentThread());
+
+  task_runner_1->PostTask(
+      FROM_HERE, BindOnce(
+                     [](scoped_refptr<SingleThreadTaskRunner> task_runner_1,
+                        scoped_refptr<SingleThreadTaskRunner> task_runner_2) {
+                       EXPECT_TRUE(task_runner_1->RunsTasksOnCurrentThread());
+                       EXPECT_FALSE(task_runner_2->RunsTasksOnCurrentThread());
+                     },
+                     task_runner_1, task_runner_2));
+
+  task_runner_2->PostTask(
+      FROM_HERE, BindOnce(
+                     [](scoped_refptr<SingleThreadTaskRunner> task_runner_1,
+                        scoped_refptr<SingleThreadTaskRunner> task_runner_2) {
+                       EXPECT_FALSE(task_runner_1->RunsTasksOnCurrentThread());
+                       EXPECT_TRUE(task_runner_2->RunsTasksOnCurrentThread());
+                     },
+                     task_runner_1, task_runner_2));
+
+  task_tracker_.Shutdown();
+}
+
+namespace {
+
+class TaskSchedulerSingleThreadTaskRunnerManagerCommonTest
+    : public TaskSchedulerSingleThreadTaskRunnerManagerTest,
+      public ::testing::WithParamInterface<SingleThreadTaskRunnerThreadMode> {
+ public:
+  TaskSchedulerSingleThreadTaskRunnerManagerCommonTest() = default;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(
+      TaskSchedulerSingleThreadTaskRunnerManagerCommonTest);
+};
+
+}  // namespace
+
+TEST_P(TaskSchedulerSingleThreadTaskRunnerManagerCommonTest,
+       PrioritySetCorrectly) {
   // Why are events used here instead of the task tracker?
   // Shutting down can cause priorities to get raised. This means we have to use
   // events to determine when a task is run.
   scoped_refptr<SingleThreadTaskRunner> task_runner_background =
       single_thread_task_runner_manager_
-          ->CreateSingleThreadTaskRunnerWithTraits("Background",
-                                                   ThreadPriority::BACKGROUND,
-                                                   {TaskPriority::BACKGROUND});
+          ->CreateSingleThreadTaskRunnerWithTraits(
+              "Background", ThreadPriority::BACKGROUND,
+              {TaskPriority::BACKGROUND}, GetParam());
   scoped_refptr<SingleThreadTaskRunner> task_runner_normal =
       single_thread_task_runner_manager_
           ->CreateSingleThreadTaskRunnerWithTraits(
-              "Normal", ThreadPriority::NORMAL, {TaskPriority::USER_VISIBLE});
+              "Normal", ThreadPriority::NORMAL, {TaskPriority::USER_VISIBLE},
+              GetParam());
 
   ThreadPriority thread_priority_background;
   task_runner_background->PostTask(
@@ -158,24 +244,27 @@ TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest, PrioritySetCorrectly) {
   EXPECT_EQ(ThreadPriority::NORMAL, thread_priority_normal);
 }
 
-TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest, PostTaskAfterShutdown) {
-  auto task_runner = single_thread_task_runner_manager_
-                         ->CreateSingleThreadTaskRunnerWithTraits(
-                             "A", ThreadPriority::NORMAL, TaskTraits());
+TEST_P(TaskSchedulerSingleThreadTaskRunnerManagerCommonTest,
+       PostTaskAfterShutdown) {
+  auto task_runner =
+      single_thread_task_runner_manager_
+          ->CreateSingleThreadTaskRunnerWithTraits("A", ThreadPriority::NORMAL,
+                                                   TaskTraits(), GetParam());
   task_tracker_.Shutdown();
   EXPECT_FALSE(task_runner->PostTask(FROM_HERE, BindOnce(&ShouldNotRun)));
 }
 
 // Verify that a Task runs shortly after its delay expires.
-TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest, PostDelayedTask) {
+TEST_P(TaskSchedulerSingleThreadTaskRunnerManagerCommonTest, PostDelayedTask) {
   TimeTicks start_time = TimeTicks::Now();
 
   // Post a task with a short delay.
   WaitableEvent task_ran(WaitableEvent::ResetPolicy::MANUAL,
                          WaitableEvent::InitialState::NOT_SIGNALED);
-  auto task_runner = single_thread_task_runner_manager_
-                         ->CreateSingleThreadTaskRunnerWithTraits(
-                             "A", ThreadPriority::NORMAL, TaskTraits());
+  auto task_runner =
+      single_thread_task_runner_manager_
+          ->CreateSingleThreadTaskRunnerWithTraits("A", ThreadPriority::NORMAL,
+                                                   TaskTraits(), GetParam());
   EXPECT_TRUE(task_runner->PostDelayedTask(
       FROM_HERE, BindOnce(&WaitableEvent::Signal, Unretained(&task_ran)),
       TestTimeouts::tiny_timeout()));
@@ -191,42 +280,11 @@ TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest, PostDelayedTask) {
             TimeDelta::FromMilliseconds(250) + TestTimeouts::tiny_timeout());
 }
 
-TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest,
-       RunsTasksOnCurrentThread) {
-  scoped_refptr<SingleThreadTaskRunner> task_runner_1 =
-      single_thread_task_runner_manager_
-          ->CreateSingleThreadTaskRunnerWithTraits(
-              "A", ThreadPriority::NORMAL,
-              {TaskShutdownBehavior::BLOCK_SHUTDOWN});
-  scoped_refptr<SingleThreadTaskRunner> task_runner_2 =
-      single_thread_task_runner_manager_
-          ->CreateSingleThreadTaskRunnerWithTraits(
-              "B", ThreadPriority::NORMAL,
-              {TaskShutdownBehavior::BLOCK_SHUTDOWN});
-
-  EXPECT_FALSE(task_runner_1->RunsTasksOnCurrentThread());
-  EXPECT_FALSE(task_runner_2->RunsTasksOnCurrentThread());
-
-  task_runner_1->PostTask(
-      FROM_HERE, BindOnce(
-                     [](scoped_refptr<SingleThreadTaskRunner> task_runner_1,
-                        scoped_refptr<SingleThreadTaskRunner> task_runner_2) {
-                       EXPECT_TRUE(task_runner_1->RunsTasksOnCurrentThread());
-                       EXPECT_FALSE(task_runner_2->RunsTasksOnCurrentThread());
-                     },
-                     task_runner_1, task_runner_2));
-
-  task_runner_2->PostTask(
-      FROM_HERE, BindOnce(
-                     [](scoped_refptr<SingleThreadTaskRunner> task_runner_1,
-                        scoped_refptr<SingleThreadTaskRunner> task_runner_2) {
-                       EXPECT_FALSE(task_runner_1->RunsTasksOnCurrentThread());
-                       EXPECT_TRUE(task_runner_2->RunsTasksOnCurrentThread());
-                     },
-                     task_runner_1, task_runner_2));
-
-  task_tracker_.Shutdown();
-}
+INSTANTIATE_TEST_CASE_P(
+    AllModes,
+    TaskSchedulerSingleThreadTaskRunnerManagerCommonTest,
+    ::testing::Values(SingleThreadTaskRunnerThreadMode::SHARED,
+                      SingleThreadTaskRunnerThreadMode::DEDICATED));
 
 namespace {
 
@@ -285,7 +343,8 @@ TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerJoinTest, ConcurrentJoin) {
     auto task_runner =
         single_thread_task_runner_manager_
             ->CreateSingleThreadTaskRunnerWithTraits(
-                "A", ThreadPriority::NORMAL, {WithBaseSyncPrimitives()});
+                "A", ThreadPriority::NORMAL, {WithBaseSyncPrimitives()},
+                SingleThreadTaskRunnerThreadMode::DEDICATED);
     EXPECT_TRUE(task_runner->PostTask(
         FROM_HERE,
         BindOnce(&WaitableEvent::Signal, Unretained(&task_running))));
@@ -315,7 +374,8 @@ TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerJoinTest,
     auto task_runner =
         single_thread_task_runner_manager_
             ->CreateSingleThreadTaskRunnerWithTraits(
-                "A", ThreadPriority::NORMAL, {WithBaseSyncPrimitives()});
+                "A", ThreadPriority::NORMAL, {WithBaseSyncPrimitives()},
+                SingleThreadTaskRunnerThreadMode::DEDICATED);
     EXPECT_TRUE(task_runner->PostTask(
         FROM_HERE,
         BindOnce(&WaitableEvent::Signal, Unretained(&task_running))));
@@ -335,10 +395,12 @@ TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerJoinTest,
 
 #if defined(OS_WIN)
 
-TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest, COMSTAInitialized) {
+TEST_P(TaskSchedulerSingleThreadTaskRunnerManagerCommonTest,
+       COMSTAInitialized) {
   scoped_refptr<SingleThreadTaskRunner> com_task_runner =
       single_thread_task_runner_manager_->CreateCOMSTATaskRunnerWithTraits(
-          "A", ThreadPriority::NORMAL, {TaskShutdownBehavior::BLOCK_SHUTDOWN});
+          "A", ThreadPriority::NORMAL, {TaskShutdownBehavior::BLOCK_SHUTDOWN},
+          GetParam());
 
   com_task_runner->PostTask(
       FROM_HERE, BindOnce([]() {
@@ -352,6 +414,30 @@ TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest, COMSTAInitialized) {
   task_tracker_.Shutdown();
 }
 
+TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTest, COMSTASameThreadUsed) {
+  scoped_refptr<SingleThreadTaskRunner> task_runner_1 =
+      single_thread_task_runner_manager_->CreateCOMSTATaskRunnerWithTraits(
+          "A", ThreadPriority::NORMAL, {TaskShutdownBehavior::BLOCK_SHUTDOWN},
+          SingleThreadTaskRunnerThreadMode::SHARED);
+  scoped_refptr<SingleThreadTaskRunner> task_runner_2 =
+      single_thread_task_runner_manager_->CreateCOMSTATaskRunnerWithTraits(
+          "B", ThreadPriority::NORMAL, {TaskShutdownBehavior::BLOCK_SHUTDOWN},
+          SingleThreadTaskRunnerThreadMode::SHARED);
+
+  PlatformThreadRef thread_ref_1;
+  task_runner_1->PostTask(FROM_HERE,
+                          BindOnce(&CaptureThreadRef, &thread_ref_1));
+  PlatformThreadRef thread_ref_2;
+  task_runner_2->PostTask(FROM_HERE,
+                          BindOnce(&CaptureThreadRef, &thread_ref_2));
+
+  task_tracker_.Shutdown();
+
+  ASSERT_FALSE(thread_ref_1.is_null());
+  ASSERT_FALSE(thread_ref_2.is_null());
+  EXPECT_EQ(thread_ref_1, thread_ref_2);
+}
+
 namespace {
 
 const wchar_t* const kTestWindowClassName =
@@ -400,7 +486,8 @@ class TaskSchedulerSingleThreadTaskRunnerManagerTestWin
 TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerTestWin, PumpsMessages) {
   scoped_refptr<SingleThreadTaskRunner> com_task_runner =
       single_thread_task_runner_manager_->CreateCOMSTATaskRunnerWithTraits(
-          "A", ThreadPriority::NORMAL, {TaskShutdownBehavior::BLOCK_SHUTDOWN});
+          "A", ThreadPriority::NORMAL, {TaskShutdownBehavior::BLOCK_SHUTDOWN},
+          SingleThreadTaskRunnerThreadMode::DEDICATED);
   HWND hwnd = nullptr;
   // HWNDs process messages on the thread that created them, so we have to
   // create them within the context of the task runner to properly simulate a
@@ -451,8 +538,9 @@ TEST_F(TaskSchedulerSingleThreadTaskRunnerManagerStartTest,
   WaitableEvent task_running(WaitableEvent::ResetPolicy::MANUAL,
                              WaitableEvent::InitialState::NOT_SIGNALED);
   single_thread_task_runner_manager_
-      ->CreateSingleThreadTaskRunnerWithTraits("A", ThreadPriority::NORMAL,
-                                               TaskTraits())
+      ->CreateSingleThreadTaskRunnerWithTraits(
+          "A", ThreadPriority::NORMAL, TaskTraits(),
+          SingleThreadTaskRunnerThreadMode::DEDICATED)
       ->PostTask(
           FROM_HERE,
           BindOnce(