Test using a global, replacable TaskQueueImpl factory.

webrtc/rtc_base/task_queue_impl_factory.h

+/*
+ *  Copyright 2017 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_RTC_BASE_TASK_QUEUE_IMPL_FACTORY_H_
+#define WEBRTC_RTC_BASE_TASK_QUEUE_IMPL_FACTORY_H_
+
+#include "webrtc/rtc_base/scoped_ref_ptr.h"
+#include "webrtc/rtc_base/task_queue.h"
+#include "webrtc/rtc_base/task_queue_impl.h"
+
+namespace rtc {
+
+class TaskQueueImplFactory {
+ public:
+  virtual ~TaskQueueImplFactory() = default;
+
+  virtual scoped_refptr<TaskQueueImpl> CreateImpl(

[nisse-webrtc, 2017/08/18 11:45:45]

Naming: I'd prefer any of CreateTaskQueueImpl, CreateTQ or Create over
CreateImpl. "Impl" adds very little meaning per character.

+      const char* queue_name,
+      TaskQueue* queue,  // only used for GetCurrent()
+      TaskQueue::Priority priority) = 0;
+
+  virtual TaskQueue* CurrentQueue() = 0;
+
+  // Sets the factory to be used by this process. May only be called once
+  // before any TaskQueues are created.
+  static void Set(TaskQueueImplFactory* factory);
+  static TaskQueueImplFactory* Get();
+};
+
+#if defined(WEBRTC_LINUX)
+class TaskQueueLibEventFactory : public TaskQueueImplFactory {

[kwiberg-webrtc, 2017/08/21 09:21:55]

Does this class definition need to be here, in a header? It's usually possible
to put interface implementations in a .cc file together with the definition of
the function that instantiates them.

+ public:
+  TaskQueueLibEventFactory() = default;
+  ~TaskQueueLibEventFactory() override = default;

[kwiberg-webrtc, 2017/08/21 09:21:55]

Do you need these two?

+  // TaskQueueLibEventFactory is neither copyable nor movable.
+  TaskQueueLibEventFactory(const TaskQueueLibEventFactory&) = delete;
+  TaskQueueLibEventFactory& operator=(const TaskQueueLibEventFactory&) = delete;

[kwiberg-webrtc, 2017/08/21 09:21:55]

I don't think you need these two. Copying or moving isn't useful, but not
harmful either.

+
+  scoped_refptr<TaskQueueImpl> CreateImpl(
+      const char* queue_name,
+      TaskQueue* queue,
+      TaskQueue::Priority priority) override;
+
+  TaskQueue* CurrentQueue() override;
+};
+#endif
+
+}  // namespace rtc
+#endif  // WEBRTC_RTC_BASE_TASK_QUEUE_IMPL_FACTORY_H_