Expose codec implementation names in stats.

talk/app/webrtc/java/jni/androidmediadecoder_jni.cc

Index: talk/app/webrtc/java/jni/androidmediadecoder_jni.cc
diff --git a/talk/app/webrtc/java/jni/androidmediadecoder_jni.cc b/talk/app/webrtc/java/jni/androidmediadecoder_jni.cc
index 618c119371ecdbb7e710ead4cbb582d6a93b3ebf..4de587921ffffc907b46caf17eb69182bc6f874a 100644
--- a/talk/app/webrtc/java/jni/androidmediadecoder_jni.cc
+++ b/talk/app/webrtc/java/jni/androidmediadecoder_jni.cc
@@ -90,6 +90,8 @@ class MediaCodecVideoDecoder : public webrtc::VideoDecoder,
   // rtc::MessageHandler implementation.
   void OnMessage(rtc::Message* msg) override;
 
+  const char* ImplementationName() const override;
+
  private:
   // CHECK-fail if not running on |codec_thread_|.
   void CheckOnCodecThread();
@@ -852,5 +854,9 @@ void MediaCodecVideoDecoderFactory::DestroyVideoDecoder(
   delete decoder;
 }
 
+const char* MediaCodecVideoDecoder::ImplementationName() const {
+  return "MediaCodec";
+}
+
 }  // namespace webrtc_jni