[chromcast] Still need to call StreamMixerAlsa::SetVolume, even when ALSA doesn't own the volume.

chromecast/media/cma/backend/alsa/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/buildflag_header.gni")
 import("//build/config/chromecast_build.gni")
 import("//chromecast/chromecast.gni")
 import("//media/media_options.gni")
 import("//testing/test.gni")
 
@@ skipping 92 matching lines @@
   sources = [
     "slew_volume.cc",
     "slew_volume.h",
   ]
   deps = [
     "//base",
     "//media",
   ]
 }
 
-alsa_controls_volume = !enable_assistant
+alsa_owns_volume = !enable_assistant
 
 buildflag_header("alsa_features") {
   header = "alsa_features.h"
 
   flags = [
     "ALSA_MONOTONIC_RAW_TSTAMPS=$use_alsa_monotonic_raw_tstamps",
-    "ALSA_CONTROLS_VOLUME=$alsa_controls_volume",
+    "ALSA_OWNS_VOLUME=$alsa_owns_volume",
   ]
 }
 
 test("cast_alsa_cma_backend_unittests") {
   sources = [
     "stream_mixer_alsa_unittest.cc",
   ]
 
   deps = [
     ":test_support",
@@ skipping 18 matching lines @@
   public_deps = [
     ":alsa_cma_backend",
   ]
 
   deps = [
     "//base",
     "//media",
     "//testing/gmock",
   ]
 }