Remove codec thread from MediaCodecVideoEncoder.

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

Index: webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc
diff --git a/webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc b/webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc
index ae1151162ac19376c1e6a2620b6d2b082df050f0..a4d10671ba21e9f819645ebd54682ed90e239b9d 100644
--- a/webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc
+++ b/webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc
@@ -149,6 +149,7 @@ int SimulcastEncoderAdapter::Release() {
   while (!streaminfos_.empty()) {
     VideoEncoder* encoder = streaminfos_.back().encoder;
     EncodedImageCallback* callback = streaminfos_.back().callback;
+    encoder->Release();
     factory_->Destroy(encoder);
     delete callback;
     streaminfos_.pop_back();