Add ScopedTaskEnvironment::ExecutionControlMode.

base/test/scoped_task_environment.h

 // Copyright 2017 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.
 
 #ifndef BASE_TEST_SCOPED_TASK_ENVIRONMENT_H_
 #define BASE_TEST_SCOPED_TASK_ENVIRONMENT_H_
 
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 
 namespace base {
 
 class TaskScheduler;
 
 namespace test {
 
 // ScopedTaskEnvironment allows usage of these APIs within its scope:
 // - (Thread|Sequenced)TaskRunnerHandle, on the thread where it lives
 // - base/task_scheduler/post_task.h, on any thread
 //
 // Tests that need either of these APIs should instantiate a
 // ScopedTaskEnvironment.
 //
 // Tasks posted to the (Thread|Sequenced)TaskRunnerHandle run synchronously when
 // RunLoop::Run(UntilIdle) or ScopedTaskEnvironment::RunUntilIdle is called on
 // the thread where the ScopedTaskEnvironment lives.
 //
-// Tasks posted through base/task_scheduler/post_task.h run on dedicated threads
+// Tasks posted through base/task_scheduler/post_task.h run on dedicated
+// threads. If ExecutionMode is QUEUED, they run when RunUntilIdle() or
+// ~ScopedTaskEnvironment is called. If ExecutionMode is ASYNC, they run
 // as they are posted.
 //
 // All methods of ScopedTaskEnvironment must be called from the same thread.
 //
 // Usage:
 //
 //   class MyTestFixture : public testing::Test {
 //    public:
 //     (...)
 //
@@ skipping 14 matching lines @@
  public:
   enum class MainThreadType {
     // The main thread doesn't pump system messages.
     DEFAULT,
     // The main thread pumps UI messages.
     UI,
     // The main thread pumps asynchronous IO messages.
     IO,
   };
 
+  enum class ExecutionMode {
+    // Tasks are queued and only executed when RunUntilIdle() is explicitly
+    // called.
+    QUEUED,
+    // Tasks run as they are posted. RunUntilIdle() can still be used to block
+    // until done.
+    ASYNC,
+  };
+
   ScopedTaskEnvironment(
-      MainThreadType main_thread_type = MainThreadType::DEFAULT);
+      MainThreadType main_thread_type = MainThreadType::DEFAULT,
+      ExecutionMode execution_control_mode = ExecutionMode::ASYNC);
 
   // Waits until no undelayed TaskScheduler tasks remain. Then, unregisters the
   // TaskScheduler and the (Thread|Sequenced)TaskRunnerHandle.
   ~ScopedTaskEnvironment();
 
   // Returns a TaskRunner that schedules tasks on the main thread.
   scoped_refptr<base::SingleThreadTaskRunner> GetMainThreadTaskRunner();
 
-  // Synchronously runs (Thread|Sequenced)TaskRunnerHandle tasks until no
-  // undelayed (Thread|Sequenced)TaskRunnerHandle or TaskScheduler tasks remain.
+  // Runs tasks until both the (Thread|Sequenced)TaskRunnerHandle and the
+  // TaskScheduler queues are empty.
   void RunUntilIdle();
 
  private:
+  class TestTaskTracker;
+
+  const ExecutionMode execution_control_mode_;
+
   // Note: |message_loop_| is an implementation detail and will be replaced in
   // the future, do NOT rely on the presence of a MessageLoop beyond
   // (Thread|Sequenced)TaskRunnerHandle and RunLoop.
   MessageLoop message_loop_;
 
   const TaskScheduler* task_scheduler_ = nullptr;
 
+  // Owned by |task_scheduler_|.
+  TestTaskTracker* const task_tracker_;
+
   DISALLOW_COPY_AND_ASSIGN(ScopedTaskEnvironment);
 };
 
 }  // namespace test
 }  // namespace base
 
 #endif  // BASE_TEST_SCOPED_ASYNC_TASK_SCHEDULER_H_