Remove the last piece of deprecated synchronous IO code.

media/audio/fake_audio_manager.cc

Index: media/audio/fake_audio_manager.cc
diff --git a/media/audio/fake_audio_manager.cc b/media/audio/fake_audio_manager.cc
index e5d9bd4d8c8658df6056269dfd6b42017130e29a..a181a2f263115195e5debd86398a554e8f8f175c 100644
--- a/media/audio/fake_audio_manager.cc
+++ b/media/audio/fake_audio_manager.cc
@@ -58,17 +58,15 @@ AudioParameters FakeAudioManager::GetPreferredOutputStreamParameters(
   int sample_rate = kDefaultSampleRate;
   int buffer_size = kDefaultOutputBufferSize;
   int bits_per_sample = 16;
-  int input_channels = 0;
   if (input_params.IsValid()) {
     sample_rate = input_params.sample_rate();
     bits_per_sample = input_params.bits_per_sample();
     channel_layout = input_params.channel_layout();
-    input_channels = input_params.input_channels();
     buffer_size = std::min(input_params.frames_per_buffer(), buffer_size);
   }
 
   return AudioParameters(
-      AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout, input_channels,
+      AudioParameters::AUDIO_PCM_LOW_LATENCY, channel_layout,
       sample_rate, bits_per_sample, buffer_size, AudioParameters::NO_EFFECTS);
 }