Replace AudioDecoderConfig with simple accessors on AudioDecoder.

media/filters/null_audio_renderer.cc

Index: media/filters/null_audio_renderer.cc
diff --git a/media/filters/null_audio_renderer.cc b/media/filters/null_audio_renderer.cc
index 21b3e07d7081add8397f39b37e2da0dd040365c0..0d5daf59599e8c74fe863798adf3000b2eb93669 100644
--- a/media/filters/null_audio_renderer.cc
+++ b/media/filters/null_audio_renderer.cc
@@ -60,11 +60,13 @@ void NullAudioRenderer::ThreadMain() {
   }
 }
 
-bool NullAudioRenderer::OnInitialize(const AudioDecoderConfig& config) {
+bool NullAudioRenderer::OnInitialize(int bits_per_channel,
+                                     ChannelLayout channel_layout,
+                                     int sample_rate) {
   // Calculate our bytes per millisecond value and allocate our buffer.
   bytes_per_millisecond_ =
-      (ChannelLayoutToChannelCount(config.channel_layout) * config.sample_rate *
-       config.bits_per_channel / 8) / base::Time::kMillisecondsPerSecond;
+      (ChannelLayoutToChannelCount(channel_layout) * sample_rate *
+       bits_per_channel / 8) / base::Time::kMillisecondsPerSecond;
   buffer_size_ = bytes_per_millisecond_ * kBufferSizeInMilliseconds;
   buffer_.reset(new uint8[buffer_size_]);
   DCHECK(buffer_.get());