[H264][Simulcast] Implement the simulcast logic for h264 encoder

webrtc/media/engine/webrtcvideoengine2.cc

 /*
  *  Copyright (c) 2014 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.
  */
 
@@ skipping 278 matching lines @@
       LOG(LS_WARNING) << "Conflict merging red_rtx_payload_type configs: "
                       << output->red_rtx_payload_type << " and "
                       << other.red_rtx_payload_type;
     }
     output->red_rtx_payload_type = other.red_rtx_payload_type;
   }
 }
 
 // Returns true if the given codec is disallowed from doing simulcast.
 bool IsCodecBlacklistedForSimulcast(const std::string& codec_name) {
-  return CodecNamesEq(codec_name, kH264CodecName) ||
-         CodecNamesEq(codec_name, kVp9CodecName);
+  return CodecNamesEq(codec_name, kVp9CodecName);
 }
 
 // The selected thresholds for QVGA and VGA corresponded to a QP around 10.
 // The change in QP declined above the selected bitrates.
 static int GetMaxDefaultVideoBitrateKbps(int width, int height) {
   if (width * height <= 320 * 240) {
     return 600;
   } else if (width * height <= 640 * 480) {
     return 1700;
   } else if (width * height <= 960 * 540) {
@@ skipping 2275 matching lines @@
         rtx_mapping[video_codecs[i].codec.id] !=
             fec_settings.red_payload_type) {
       video_codecs[i].rtx_payload_type = rtx_mapping[video_codecs[i].codec.id];
     }
   }
 
   return video_codecs;
 }
 
 }  // namespace cricket