Move scalability structures from av1 into own subfolder

To make it natural to reuse them for vp9

Bug: webrtc:11999
Change-Id: If2ef7ca16b8be96e0e03bb19211d9f5eb74b2d3d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/188620
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32414}

modules/video_coding/svc/create_scalability_structure.cc

@@ -0,0 +1,73 @@
+/*
+ *  Copyright (c) 2020 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.
+ */
+#include "modules/video_coding/svc/create_scalability_structure.h"
+
+#include <memory>
+
+#include "absl/strings/string_view.h"
+#include "modules/video_coding/svc/scalability_structure_l1t2.h"
+#include "modules/video_coding/svc/scalability_structure_l1t3.h"
+#include "modules/video_coding/svc/scalability_structure_l2t1.h"
+#include "modules/video_coding/svc/scalability_structure_l2t1_key.h"
+#include "modules/video_coding/svc/scalability_structure_l2t1h.h"
+#include "modules/video_coding/svc/scalability_structure_l2t2.h"
+#include "modules/video_coding/svc/scalability_structure_l2t2_key.h"
+#include "modules/video_coding/svc/scalability_structure_l2t2_key_shift.h"
+#include "modules/video_coding/svc/scalability_structure_l3t1.h"
+#include "modules/video_coding/svc/scalability_structure_l3t3.h"
+#include "modules/video_coding/svc/scalability_structure_s2t1.h"
+#include "modules/video_coding/svc/scalable_video_controller.h"
+#include "modules/video_coding/svc/scalable_video_controller_no_layering.h"
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+namespace {
+
+struct NamedStructureFactory {
+  absl::string_view name;
+  // Use function pointer to make NamedStructureFactory trivally destructable.
+  std::unique_ptr<ScalableVideoController> (*factory)();
+};
+
+// Wrap std::make_unique function to have correct return type.
+template <typename T>
+std::unique_ptr<ScalableVideoController> Create() {
+  return std::make_unique<T>();
+}
+
+constexpr NamedStructureFactory kFactories[] = {
+    {"NONE", Create<ScalableVideoControllerNoLayering>},
+    {"L1T2", Create<ScalabilityStructureL1T2>},
+    {"L1T3", Create<ScalabilityStructureL1T3>},
+    {"L2T1", Create<ScalabilityStructureL2T1>},
+    {"L2T1h", Create<ScalabilityStructureL2T1h>},
+    {"L2T1_KEY", Create<ScalabilityStructureL2T1Key>},
+    {"L2T2", Create<ScalabilityStructureL2T2>},
+    {"L2T2_KEY", Create<ScalabilityStructureL2T2Key>},
+    {"L2T2_KEY_SHIFT", Create<ScalabilityStructureL2T2KeyShift>},
+    {"L3T1", Create<ScalabilityStructureL3T1>},
+    {"L3T3", Create<ScalabilityStructureL3T3>},
+    {"S2T1", Create<ScalabilityStructureS2T1>},
+};
+
+}  // namespace
+
+std::unique_ptr<ScalableVideoController> CreateScalabilityStructure(
+    absl::string_view name) {
+  RTC_DCHECK(!name.empty());
+  for (const auto& entry : kFactories) {
+    if (entry.name == name) {
+      return entry.factory();
+    }
+  }
+  return nullptr;
+}
+
+}  // namespace webrtc