Video bitrate allocator factory interface for custom video bitrate allocator

Bug: webrtc:9513
Change-Id: If5719f4f71a2a9e44b2aaa0b592d3921b68ba5d9
Reviewed-on: https://webrtc-review.googlesource.com/92280
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Commit-Queue: Jiawei Ou <ouj@fb.com>
Cr-Commit-Position: refs/heads/master@{#24279}

api/video/BUILD.gn

@@ -101,6 +101,17 @@ rtc_source_set("video_bitrate_allocator") {
   ]
 }
 
+rtc_source_set("video_bitrate_allocator_factory") {
+  visibility = [ "*" ]
+  sources = [
+    "video_bitrate_allocator_factory.h",
+  ]
+  deps = [
+    ":video_bitrate_allocator",
+    "../../media:rtc_media_base",
+  ]
+}
+
 rtc_source_set("video_stream_decoder") {
   visibility = [ "*" ]
   sources = [

api/video/video_bitrate_allocator_factory.h

@@ -0,0 +1,32 @@
+/*
+ *  Copyright (c) 2018 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 API_VIDEO_VIDEO_BITRATE_ALLOCATOR_FACTORY_H_
+#define API_VIDEO_VIDEO_BITRATE_ALLOCATOR_FACTORY_H_
+
+#include <memory>
+#include "api/video/video_bitrate_allocator.h"
+#include "media/base/codec.h"
+
+namespace webrtc {
+
+// A factory that creates VideoBitrateAllocator.
+// NOTE: This class is still under development and may change without notice.
+class VideoBitrateAllocatorFactory {
+ public:
+  virtual ~VideoBitrateAllocatorFactory() = default;
+  // Creates a VideoBitrateAllocator for a specific video codec.
+  virtual std::unique_ptr<VideoBitrateAllocator> CreateVideoBitrateAllocator(
+      const VideoCodec& codec) = 0;
+};
+
+}  // namespace webrtc
+
+#endif  // API_VIDEO_VIDEO_BITRATE_ALLOCATOR_FACTORY_H_