Convert MediaLog from being ref counted to owned by WebMediaPlayer.

chromecast/media/cma/decoder/cast_audio_decoder_linux.cc

Index: chromecast/media/cma/decoder/cast_audio_decoder_linux.cc
diff --git a/chromecast/media/cma/decoder/cast_audio_decoder_linux.cc b/chromecast/media/cma/decoder/cast_audio_decoder_linux.cc
index 2ef1fa40c7b600f88e7f2b98ede5b6e108204bea..2201380975be233c5eccd94a92a94103b64281c1 100644
--- a/chromecast/media/cma/decoder/cast_audio_decoder_linux.cc
+++ b/chromecast/media/cma/decoder/cast_audio_decoder_linux.cc
@@ -68,8 +68,7 @@ class CastAudioDecoderImpl : public CastAudioDecoder {
                                              ::media::CHANNEL_LAYOUT_STEREO));
     }
     base::WeakPtr<CastAudioDecoderImpl> self = weak_factory_.GetWeakPtr();
-    decoder_.reset(new ::media::FFmpegAudioDecoder(
-        task_runner_, make_scoped_refptr(new ::media::MediaLog())));
+    decoder_.reset(new ::media::FFmpegAudioDecoder(task_runner_, &media_log_));
     decoder_->Initialize(
         media::DecoderConfigAdapter::ToMediaAudioDecoderConfig(config_),
         nullptr, base::Bind(&CastAudioDecoderImpl::OnInitialized, self),
@@ -246,6 +245,7 @@ class CastAudioDecoderImpl : public CastAudioDecoder {
         new media::DecoderBufferAdapter(config_.id, result));
   }
 
+  ::media::MediaLog media_log_;
   const scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   InitializedCallback initialized_callback_;
   OutputFormat output_format_;