Revert of Turn off error resilience for VP9 if no spatial or temporal layers are configured and NACK is enabl… (patchset #1 id:40001 of https://codereview.webrtc.org/2532053002/ )

Reason for revert:
Increase in encode time larger than expected.

Original issue's description:
> Turn off error resilience for VP9 if no spatial or temporal layers are configured and NACK is enabled.
>
> Error resilience is currently always enabled for VP9 which reduces quality.
>
> BUG=webrtc:6783
>
> Committed: https://crrev.com/4eb03c76fa2320534d669fda2aabf800e7a6f579
> Cr-Commit-Position: refs/heads/master@{#15390}

TBR=stefan@webrtc.org,marpan@webrtc.org,mflodman@webrtc.org,marpan@google.com
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=webrtc:6783

Review-Url: https://codereview.webrtc.org/2554403006
Cr-Commit-Position: refs/heads/master@{#15501}
diff --git a/webrtc/modules/video_coding/codec_database.cc b/webrtc/modules/video_coding/codec_database.cc
index 40e31c6..75e7043 100644
--- a/webrtc/modules/video_coding/codec_database.cc
+++ b/webrtc/modules/video_coding/codec_database.cc
@@ -46,7 +46,7 @@
   VideoCodecVP9 vp9_settings;
   memset(&vp9_settings, 0, sizeof(vp9_settings));
 
-  vp9_settings.resilienceOn = true;
+  vp9_settings.resilience = 1;
   vp9_settings.numberOfTemporalLayers = 1;
   vp9_settings.denoisingOn = false;
   vp9_settings.frameDroppingOn = true;
diff --git a/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc b/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
index f8b6e1b..bfb5606 100644
--- a/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
+++ b/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
@@ -298,7 +298,7 @@
   config_->g_w = codec_.width;
   config_->g_h = codec_.height;
   config_->rc_target_bitrate = inst->startBitrate;  // in kbit/s
-  config_->g_error_resilient = inst->VP9().resilienceOn ? 1 : 0;
+  config_->g_error_resilient = 1;
   // Setting the time base of the codec.
   config_->g_timebase.num = 1;
   config_->g_timebase.den = 90000;
diff --git a/webrtc/modules/video_coding/video_codec_initializer.cc b/webrtc/modules/video_coding/video_codec_initializer.cc
index d7b6131..dbdede0 100644
--- a/webrtc/modules/video_coding/video_codec_initializer.cc
+++ b/webrtc/modules/video_coding/video_codec_initializer.cc
@@ -21,15 +21,6 @@
 #include "webrtc/system_wrappers/include/clock.h"
 
 namespace webrtc {
-namespace {
-bool TemporalLayersConfigured(const std::vector<VideoStream>& streams) {
-  for (const VideoStream& stream : streams) {
-    if (stream.temporal_layer_thresholds_bps.size() > 0)
-      return true;
-  }
-  return false;
-}
-}  // namespace
 
 bool VideoCodecInitializer::SetupCodec(
     const VideoEncoderConfig& config,
@@ -128,8 +119,12 @@
         *video_codec.VP8() = VideoEncoder::GetDefaultVp8Settings();
       video_codec.VP8()->numberOfTemporalLayers = static_cast<unsigned char>(
           streams.back().temporal_layer_thresholds_bps.size() + 1);
-
-      if (nack_enabled && !TemporalLayersConfigured(streams)) {
+      bool temporal_layers_configured = false;
+      for (const VideoStream& stream : streams) {
+        if (stream.temporal_layer_thresholds_bps.size() > 0)
+          temporal_layers_configured = true;
+      }
+      if (nack_enabled && !temporal_layers_configured) {
         LOG(LS_INFO) << "No temporal layers and nack enabled -> resilience off";
         video_codec.VP8()->resilience = kResilienceOff;
       }
@@ -147,13 +142,6 @@
       }
       video_codec.VP9()->numberOfTemporalLayers = static_cast<unsigned char>(
           streams.back().temporal_layer_thresholds_bps.size() + 1);
-
-      if (nack_enabled && !TemporalLayersConfigured(streams) &&
-          video_codec.VP9()->numberOfSpatialLayers == 1) {
-        LOG(LS_INFO) << "No temporal or spatial layers and nack enabled -> "
-                     << "resilience off";
-        video_codec.VP9()->resilienceOn = false;
-      }
       break;
     }
     case kVideoCodecH264: {