Add some virtual and OVERRIDEs in webrtc/modules/audio_coding/

BUG=163
TBR=turaj@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/1900004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4447 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_coding/neteq4/decoder_database.cc

@@ -17,10 +17,19 @@
 
 namespace webrtc {
 
+DecoderDatabase::DecoderDatabase()
+    : active_decoder_(-1), active_cng_decoder_(-1) {}
+
+DecoderDatabase::~DecoderDatabase() {}
+
 DecoderDatabase::DecoderInfo::~DecoderInfo() {
   if (!external) delete decoder;
 }
 
+bool DecoderDatabase::Empty() const { return decoders_.empty(); }
+
+int DecoderDatabase::Size() const { return decoders_.size(); }
+
 void DecoderDatabase::Reset() {
   decoders_.clear();
   active_decoder_ = -1;