output/Source: move code to DropCurrentChunk()

src/output/Source.cxx

@@ -216,7 +216,7 @@ AudioOutputSource::Fill(Mutex &mutex)
 {
 	if (current_chunk != nullptr && pending_tag == nullptr &&
 	    pending_data.empty())
-		pipe.Consume(*std::exchange(current_chunk, nullptr));
+		DropCurrentChunk();
 
 	if (current_chunk != nullptr)
 		return true;
@@ -247,7 +247,7 @@ AudioOutputSource::ConsumeData(size_t nbytes) noexcept
 	pending_data.skip_front(nbytes);
 
 	if (pending_data.empty())
-		pipe.Consume(*std::exchange(current_chunk, nullptr));
+		DropCurrentChunk();
 }
 
 ConstBuffer<void>

src/output/Source.hxx

@@ -212,6 +212,12 @@ private:
 				       unsigned *replay_gain_serial_p);
 
 	ConstBuffer<void> FilterChunk(const MusicChunk &chunk);
+
+	void DropCurrentChunk() noexcept {
+		assert(current_chunk != nullptr);
+
+		pipe.Consume(*std::exchange(current_chunk, nullptr));
+	}
 };
 
 #endif