Revert of Remove the deprecated EncodeInternal interface from AudioEncoder

webrtc/modules/audio_coding/codecs/mock/mock_audio_encoder.cc

Index: webrtc/modules/audio_coding/codecs/mock/mock_audio_encoder.cc
diff --git a/webrtc/modules/audio_coding/codecs/mock/mock_audio_encoder.cc b/webrtc/modules/audio_coding/codecs/mock/mock_audio_encoder.cc
index a674eba660748924789d1b4a834bfd221de8bcd1..52849691ac6cebc67266d088ef102b3492acbe3a 100644
--- a/webrtc/modules/audio_coding/codecs/mock/mock_audio_encoder.cc
+++ b/webrtc/modules/audio_coding/codecs/mock/mock_audio_encoder.cc
@@ -49,4 +49,26 @@
   return info_;
 }
 
+MockAudioEncoderDeprecated::CopyEncoding::CopyEncoding(
+    AudioEncoder::EncodedInfo info,
+    rtc::ArrayView<const uint8_t> payload)
+    : info_(info), payload_(payload) { }
+
+MockAudioEncoderDeprecated::CopyEncoding::CopyEncoding(
+    rtc::ArrayView<const uint8_t> payload)
+    : payload_(payload) {
+  info_.encoded_bytes = payload_.size();
+}
+
+AudioEncoder::EncodedInfo MockAudioEncoderDeprecated::CopyEncoding::operator()(
+    uint32_t timestamp,
+    rtc::ArrayView<const int16_t> audio,
+    size_t max_bytes_encoded,
+    uint8_t* encoded) {
+  RTC_CHECK(encoded);
+  RTC_CHECK_LE(info_.encoded_bytes, payload_.size());
+  std::memcpy(encoded, payload_.data(), info_.encoded_bytes);
+  return info_;
+}
+
 }  // namespace webrtc