TaskScheduler: Make the worker pools of TaskSchedulerImpl configurable

base/task_scheduler/task_scheduler_impl_unittest.cc

Index: base/task_scheduler/task_scheduler_impl_unittest.cc
diff --git a/base/task_scheduler/task_scheduler_impl_unittest.cc b/base/task_scheduler/task_scheduler_impl_unittest.cc
index 50e0caeb1c7059f467376c2ac7311a3eb01e841f..e2fc882fccf10631eee660ae5c4023c3be797ffd 100644
--- a/base/task_scheduler/task_scheduler_impl_unittest.cc
+++ b/base/task_scheduler/task_scheduler_impl_unittest.cc
@@ -38,13 +38,58 @@ struct TraitsExecutionModePair {
   ExecutionMode execution_mode;
 };
 
+class TestTaskSchedulerImplDelegate : public TaskSchedulerImpl::Delegate {
+ public:
+  using ThreadPoolCreationArgs =
+      TaskSchedulerImpl::Delegate::ThreadPoolCreationArgs;
+
+  TestTaskSchedulerImplDelegate() = default;
+  ~TestTaskSchedulerImplDelegate() = default;
+
+  size_t GetNumThreadPools() override { return 4; }
+
+  ThreadPoolCreationArgs GetCreationArgsForThreadPool(size_t pool_index) {
+    switch (pool_index) {
+      case 0:
+        return ThreadPoolCreationArgs{
+            std::string("Background"), ThreadPriority::BACKGROUND,
+            SchedulerThreadPoolImpl::IORestriction::DISALLOWED, 1U};
+      case 1:
+        return ThreadPoolCreationArgs{
+            "BackgroundFileIO", ThreadPriority::BACKGROUND,
+            SchedulerThreadPoolImpl::IORestriction::ALLOWED, 3U};
+      case 2:
+        return ThreadPoolCreationArgs{
+            "Foreground", ThreadPriority::NORMAL,
+            SchedulerThreadPoolImpl::IORestriction::DISALLOWED, 4U};
+      case 3:
+        return ThreadPoolCreationArgs{
+            "ForegroundFileIO", ThreadPriority::NORMAL,
+            SchedulerThreadPoolImpl::IORestriction::ALLOWED, 12U};
+      default:
+        ADD_FAILURE() << "Requested creation args for invalid pool index.";
+        return ThreadPoolCreationArgs{};
+    }
+  }
+
+  size_t GetThreadPoolIndexForTraits(const TaskTraits& traits) override {
+    if (traits.with_file_io())
+      return traits.priority() == TaskPriority::BACKGROUND ? 1U : 3U;
+    return traits.priority() == TaskPriority::BACKGROUND ? 0U : 2U;
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TestTaskSchedulerImplDelegate);
+};
+
 class TaskSchedulerImplTest
     : public testing::TestWithParam<TraitsExecutionModePair> {
  protected:
   TaskSchedulerImplTest() = default;
 
   void SetUp() override {
-    scheduler_ = TaskSchedulerImpl::Create();
+    scheduler_ = TaskSchedulerImpl::Create(
+        WrapUnique(new TestTaskSchedulerImplDelegate));
     EXPECT_TRUE(scheduler_);
   }
   void TearDown() override { scheduler_->JoinForTesting(); }
@@ -195,7 +240,8 @@ INSTANTIATE_TEST_CASE_P(OneTraitsExecutionModePair,
 // the expected priority and I/O restrictions and respects the characteristics
 // of its ExecutionMode.
 TEST(TaskSchedulerImplTest, MultipleTraitsExecutionModePairs) {
-  std::unique_ptr<TaskSchedulerImpl> scheduler = TaskSchedulerImpl::Create();
+  std::unique_ptr<TaskSchedulerImpl> scheduler =
+      TaskSchedulerImpl::Create(WrapUnique(new TestTaskSchedulerImplDelegate));
 
   std::vector<std::unique_ptr<ThreadPostingTasks>> threads_posting_tasks;
   for (const auto& traits_execution_mode_pair : GetTraitsExecutionModePairs()) {