Add ImplementationName to SimulcastEncoderAdapter.

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 6abb435441ba6eac91d174a7ffea457cdc7c909b..40e438f7e424c90a03727053443bb67ff90dd523 100644
--- a/webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc
+++ b/webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc
@@ -496,4 +496,11 @@ bool SimulcastEncoderAdapter::SupportsNativeHandle() const {
   return streaminfos_[0].encoder->SupportsNativeHandle();
 }
 
+const char* SimulcastEncoderAdapter::ImplementationName() const {
+  // We should not be calling this method before streaminfos_ are configured.
+  RTC_DCHECK(!streaminfos_.empty());
+  // TODO(pbos): Support multiple implementation names for different encoders.
+  return streaminfos_[0].encoder->ImplementationName();
+}
+
 }  // namespace webrtc