A few simplifications to CodecDatabase and VCMGenericDecoder

webrtc/modules/video_coding/codec_database.cc

Index: webrtc/modules/video_coding/codec_database.cc
diff --git a/webrtc/modules/video_coding/codec_database.cc b/webrtc/modules/video_coding/codec_database.cc
index 92ae5d23b5a71ffb33231446036559b0b5323f3f..2f5e7fbc3874451c5e5cfb48bcb163395a6b405f 100644
--- a/webrtc/modules/video_coding/codec_database.cc
+++ b/webrtc/modules/video_coding/codec_database.cc
@@ -71,6 +71,31 @@ VideoCodecH264 VideoEncoder::GetDefaultH264Settings() {
   return h264_settings;
 }
 
+// Create an internal Decoder given a codec type
+static std::unique_ptr<VCMGenericDecoder> CreateDecoder(VideoCodecType type) {
+  switch (type) {
+    case kVideoCodecVP8:
+      return std::unique_ptr<VCMGenericDecoder>(
+          new VCMGenericDecoder(VP8Decoder::Create()));
+    case kVideoCodecVP9:
+      return std::unique_ptr<VCMGenericDecoder>(
+          new VCMGenericDecoder(VP9Decoder::Create()));
+    case kVideoCodecI420:
+      return std::unique_ptr<VCMGenericDecoder>(
+          new VCMGenericDecoder(new I420Decoder()));
+    case kVideoCodecH264:
+      if (H264Decoder::IsSupported()) {
+        return std::unique_ptr<VCMGenericDecoder>(
+            new VCMGenericDecoder(H264Decoder::Create()));
+      }
+      break;
+    default:
+      break;
+  }
+  LOG(LS_WARNING) << "No internal decoder of this type exists.";
+  return std::unique_ptr<VCMGenericDecoder>();
+}
+
 VCMDecoderMapItem::VCMDecoderMapItem(VideoCodec* settings,
                                      int number_of_cores,
                                      bool require_key_frame)
@@ -98,13 +123,12 @@ VCMCodecDataBase::VCMCodecDataBase(
       external_encoder_(nullptr),
       internal_source_(false),
       encoded_frame_callback_(encoded_frame_callback),
-      ptr_decoder_(nullptr),
       dec_map_(),
       dec_external_map_() {}
 
 VCMCodecDataBase::~VCMCodecDataBase() {
   DeleteEncoder();
-  ReleaseDecoder(ptr_decoder_);
+  ptr_decoder_.reset();
   for (auto& kv : dec_map_)
     delete kv.second;
   for (auto& kv : dec_external_map_)
@@ -400,11 +424,10 @@ bool VCMCodecDataBase::DeregisterExternalDecoder(uint8_t payload_type) {
   // We can't use payload_type to check if the decoder is currently in use,
   // because payload type may be out of date (e.g. before we decode the first
   // frame after RegisterReceiveCodec)
-  if (ptr_decoder_ != nullptr &&
-      ptr_decoder_->_decoder == (*it).second->external_decoder_instance) {
+  if (ptr_decoder_ &&
+      ptr_decoder_->IsSameDecoder((*it).second->external_decoder_instance)) {
     // Release it if it was registered and in use.
-    ReleaseDecoder(ptr_decoder_);
-    ptr_decoder_ = nullptr;
+    ptr_decoder_.reset();
   }
   DeregisterReceiveCodec(payload_type);
   delete it->second;
@@ -464,12 +487,11 @@ VCMGenericDecoder* VCMCodecDataBase::GetDecoder(
   RTC_DCHECK(decoded_frame_callback->UserReceiveCallback());
   uint8_t payload_type = frame.PayloadType();
   if (payload_type == receive_codec_.plType || payload_type == 0) {
-    return ptr_decoder_;
+    return ptr_decoder_.get();
   }
   // Check for exisitng decoder, if exists - delete.
   if (ptr_decoder_) {
-    ReleaseDecoder(ptr_decoder_);
-    ptr_decoder_ = nullptr;
+    ptr_decoder_.reset();
     memset(&receive_codec_, 0, sizeof(VideoCodec));
   }
   ptr_decoder_ = CreateAndInitDecoder(frame, &receive_codec_);
@@ -480,36 +502,26 @@ VCMGenericDecoder* VCMCodecDataBase::GetDecoder(
   callback->OnIncomingPayloadType(receive_codec_.plType);
   if (ptr_decoder_->RegisterDecodeCompleteCallback(decoded_frame_callback) <
       0) {
-    ReleaseDecoder(ptr_decoder_);
-    ptr_decoder_ = nullptr;
+    ptr_decoder_.reset();
     memset(&receive_codec_, 0, sizeof(VideoCodec));
     return nullptr;
   }
-  return ptr_decoder_;
+  return ptr_decoder_.get();
 }
 
-void VCMCodecDataBase::ReleaseDecoder(VCMGenericDecoder* decoder) const {
-  if (decoder) {
-    RTC_DCHECK(decoder->_decoder);
-    decoder->Release();
-    if (!decoder->External()) {
-      delete decoder->_decoder;
-    }
-    delete decoder;
-  }
+VCMGenericDecoder* VCMCodecDataBase::GetCurrentDecoder() {
+  return ptr_decoder_.get();
 }
 
 bool VCMCodecDataBase::PrefersLateDecoding() const {
-  if (!ptr_decoder_)
-    return true;
-  return ptr_decoder_->PrefersLateDecoding();
+  return ptr_decoder_ ? ptr_decoder_->PrefersLateDecoding() : true;
 }
 
 bool VCMCodecDataBase::MatchesCurrentResolution(int width, int height) const {
   return send_codec_.width == width && send_codec_.height == height;
 }
 
-VCMGenericDecoder* VCMCodecDataBase::CreateAndInitDecoder(
+std::unique_ptr<VCMGenericDecoder> VCMCodecDataBase::CreateAndInitDecoder(
     const VCMEncodedFrame& frame,
     VideoCodec* new_codec) const {
   uint8_t payload_type = frame.PayloadType();
@@ -522,13 +534,13 @@ VCMGenericDecoder* VCMCodecDataBase::CreateAndInitDecoder(
                   << static_cast<int>(payload_type);
     return nullptr;
   }
-  VCMGenericDecoder* ptr_decoder = nullptr;
+  std::unique_ptr<VCMGenericDecoder> ptr_decoder;
   const VCMExtDecoderMapItem* external_dec_item =
       FindExternalDecoderItem(payload_type);
   if (external_dec_item) {
     // External codec.
-    ptr_decoder = new VCMGenericDecoder(
-        external_dec_item->external_decoder_instance, true);
+    ptr_decoder.reset(new VCMGenericDecoder(
+        external_dec_item->external_decoder_instance, true));
   } else {
     // Create decoder.
     ptr_decoder = CreateDecoder(decoder_item->settings->codecType);
@@ -547,7 +559,6 @@ VCMGenericDecoder* VCMCodecDataBase::CreateAndInitDecoder(
   }
   if (ptr_decoder->InitDecode(decoder_item->settings.get(),
                               decoder_item->number_of_cores) < 0) {
-    ReleaseDecoder(ptr_decoder);
     return nullptr;
   }
   memcpy(new_codec, decoder_item->settings.get(), sizeof(VideoCodec));
@@ -561,26 +572,6 @@ void VCMCodecDataBase::DeleteEncoder() {
   ptr_encoder_.reset();
 }
 
-VCMGenericDecoder* VCMCodecDataBase::CreateDecoder(VideoCodecType type) const {
-  switch (type) {
-    case kVideoCodecVP8:
-      return new VCMGenericDecoder(VP8Decoder::Create());
-    case kVideoCodecVP9:
-      return new VCMGenericDecoder(VP9Decoder::Create());
-    case kVideoCodecI420:
-      return new VCMGenericDecoder(new I420Decoder());
-    case kVideoCodecH264:
-      if (H264Decoder::IsSupported()) {
-        return new VCMGenericDecoder(H264Decoder::Create());
-      }
-      break;
-    default:
-      break;
-  }
-  LOG(LS_WARNING) << "No internal decoder of this type exists.";
-  return nullptr;
-}
-
 const VCMDecoderMapItem* VCMCodecDataBase::FindDecoderItem(
     uint8_t payload_type) const {
   DecoderMap::const_iterator it = dec_map_.find(payload_type);