Add AV1 encoder&decoder wrappers for iOS SDK.

It is now possible to use AV1 encoder and decoder on iOS and test
them in apps like AppRTCMobile.

Bug: None
Change-Id: Ifae221020e5abf3809010676862eecd9ffeec5e3
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/208400
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33378}

sdk/objc/api/video_codec/RTCVideoEncoderAV1.mm

@@ -0,0 +1,35 @@
+/*
+ *  Copyright (c) 2021 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.
+ *
+ */
+
+#import <Foundation/Foundation.h>
+
+#import "RTCMacros.h"
+#import "RTCVideoEncoderAV1.h"
+#import "RTCWrappedNativeVideoEncoder.h"
+
+#include "modules/video_coding/codecs/av1/libaom_av1_encoder.h"
+
+@implementation RTC_OBJC_TYPE (RTCVideoEncoderAV1)
+
++ (id<RTC_OBJC_TYPE(RTCVideoEncoder)>)av1Encoder {
+  std::unique_ptr<webrtc::VideoEncoder> nativeEncoder(webrtc::CreateLibaomAv1Encoder());
+  if (nativeEncoder == nullptr) {
+    return nil;
+  }
+  return [[RTC_OBJC_TYPE(RTCWrappedNativeVideoEncoder) alloc]
+      initWithNativeEncoder:std::move(nativeEncoder)];
+}
+
++ (bool)isSupported {
+  return webrtc::kIsLibaomAv1EncoderSupported;
+}
+
+@end