Make AudioParameters a class instead of a struct

media/audio/audio_input_volume_unittest.cc

Index: media/audio/audio_input_volume_unittest.cc
diff --git a/media/audio/audio_input_volume_unittest.cc b/media/audio/audio_input_volume_unittest.cc
index febdb78b709e14d453ee9ada4c05291e672cd8b6..99f4e8304830cc7e8e2c5a2ef377e77d9de2f96d 100644
--- a/media/audio/audio_input_volume_unittest.cc
+++ b/media/audio/audio_input_volume_unittest.cc
@@ -46,8 +46,7 @@ class AudioInputVolumeTest : public ::testing::Test {
   AudioInputStream* CreateAndOpenStream(const std::string& device_id) {
     AudioParameters::Format format = AudioParameters::AUDIO_PCM_LOW_LATENCY;
     ChannelLayout channel_layout =
-        (media::GetAudioInputHardwareChannelCount(device_id) == 1) ?
-            CHANNEL_LAYOUT_MONO : CHANNEL_LAYOUT_STEREO;
+        media::GetAudioInputHardwareChannelLayout(device_id);
     int bits_per_sample = 16;
     int sample_rate =
         static_cast<int>(media::GetAudioInputHardwareSampleRate(device_id));