Reland of Add experimental simulcast screen content mode

webrtc/modules/video_coding/codecs/vp8/realtime_temporal_layers.cc

 /* Copyright (c) 2013 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 <stdlib.h>
@@ skipping 76 matching lines @@
  public:
   RealTimeTemporalLayers(int max_num_temporal_layers,
                          uint8_t initial_tl0_pic_idx)
       : temporal_layers_(1),
         max_temporal_layers_(max_num_temporal_layers),
         tl0_pic_idx_(initial_tl0_pic_idx),
         frame_counter_(static_cast<unsigned int>(-1)),
         timestamp_(0),
         last_base_layer_sync_(0),
         layer_ids_length_(0),
-        layer_ids_(NULL),
+        layer_ids_(nullptr),
         encode_flags_length_(0),
-        encode_flags_(NULL) {
+        encode_flags_(nullptr) {
     RTC_CHECK_GE(max_temporal_layers_, 1);
-    RTC_CHECK_GE(max_temporal_layers_, 3);
+    RTC_CHECK_LE(max_temporal_layers_, 3);
   }
 
   virtual ~RealTimeTemporalLayers() {}
 
   std::vector<uint32_t> OnRatesUpdated(int bitrate_kbps,
                                        int max_bitrate_kbps,
                                        int framerate) override {
     temporal_layers_ =
         CalculateNumberOfTemporalLayers(temporal_layers_, framerate);
     temporal_layers_ = std::min(temporal_layers_, max_temporal_layers_);
@@ skipping 190 matching lines @@
     int simulcast_id,
     int max_temporal_layers,
     uint8_t initial_tl0_pic_idx) const {
   TemporalLayers* tl =
       new RealTimeTemporalLayers(max_temporal_layers, initial_tl0_pic_idx);
   if (listener_)
     listener_->OnTemporalLayersCreated(simulcast_id, tl);
   return tl;
 }
 }  // namespace webrtc