Reland of Injectable Obj-C video codecs

webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCVideoCodec.mm

+/*
+ *  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.
+ */
+
+#import "WebRTC/RTCVideoCodec.h"
+
+#import "NSString+StdString.h"
+#import "RTCVideoCodec+Private.h"
+#import "WebRTC/RTCVideoCodecFactory.h"
+
+@implementation RTCVideoCodecInfo
+
+@synthesize payload = _payload;
+@synthesize name = _name;
+@synthesize parameters = _parameters;
+
+- (instancetype)initWithPayload:(NSInteger)payload
+                           name:(NSString *)name
+                     parameters:(NSDictionary<NSString *, NSString *> *)parameters {
+  if (self = [super init]) {
+    _payload = payload;
+    _name = name;
+    _parameters = parameters;
+  }
+
+  return self;
+}
+
+- (instancetype)initWithVideoCodec:(cricket::VideoCodec)videoCodec {
+  NSMutableDictionary *params = [NSMutableDictionary dictionary];
+  for (auto it = videoCodec.params.begin(); it != videoCodec.params.end(); ++it) {
+    [params setObject:[NSString stringForStdString:it->second]
+               forKey:[NSString stringForStdString:it->first]];
+  }
+  return [self initWithPayload:videoCodec.id
+                          name:[NSString stringForStdString:videoCodec.name]
+                    parameters:params];
+}
+
+- (cricket::VideoCodec)toCpp {
+  cricket::VideoCodec codec([NSString stdStringForString:_name]);
+  for (NSString *paramKey in _parameters.allKeys) {
+    codec.SetParam([NSString stdStringForString:paramKey],
+                   [NSString stdStringForString:_parameters[paramKey]]);
+  }
+
+  return codec;
+}
+
+@end