[Chromecast] Implement new volume control API

chromecast/media/cma/backend/alsa/stream_mixer_alsa_input.cc

Index: chromecast/media/cma/backend/alsa/stream_mixer_alsa_input.cc
diff --git a/chromecast/media/cma/backend/alsa/stream_mixer_alsa_input.cc b/chromecast/media/cma/backend/alsa/stream_mixer_alsa_input.cc
index 52883ac21c595213ff979c58884e74a34104982e..5a79b176723ae409eb7a1a25a6b154ee36011e49 100644
--- a/chromecast/media/cma/backend/alsa/stream_mixer_alsa_input.cc
+++ b/chromecast/media/cma/backend/alsa/stream_mixer_alsa_input.cc
@@ -15,10 +15,11 @@ namespace media {
 StreamMixerAlsaInput::StreamMixerAlsaInput(Delegate* delegate,
                                            int samples_per_second,
                                            bool primary,
-                                           const std::string& device_id) {
-  std::unique_ptr<StreamMixerAlsaInputImpl> impl(
-      new StreamMixerAlsaInputImpl(delegate, samples_per_second, primary,
-                                   device_id, StreamMixerAlsa::Get()));
+                                           const std::string& device_id,
+                                           AudioContentType content_type) {
+  std::unique_ptr<StreamMixerAlsaInputImpl> impl(new StreamMixerAlsaInputImpl(
+      delegate, samples_per_second, primary, device_id, content_type,
+      StreamMixerAlsa::Get()));
   impl_ = impl.get();  // Store a pointer to the impl, but the mixer owns it.
   StreamMixerAlsa::Get()->AddInput(std::move(impl));
 }