Fix chromeos=1 so Pulse is preferred when use_cras=0.

media/audio/cras/audio_manager_cras.cc

Index: media/audio/cras/audio_manager_cras.cc
diff --git a/media/audio/cras/audio_manager_cras.cc b/media/audio/cras/audio_manager_cras.cc
index 876d6ce81365e6dbe6da8bffca75adf5df9d03c8..305d5e8d21f4e63e65d0392ac53055d7d534535d 100644
--- a/media/audio/cras/audio_manager_cras.cc
+++ b/media/audio/cras/audio_manager_cras.cc
@@ -138,4 +138,19 @@ AudioInputStream* AudioManagerCras::MakeInputStream(
   return new CrasInputStream(params, this, device_id);
 }
 
+snd_pcm_format_t AudioManagerCras::BitsToFormat(int bits_per_sample) {
+  switch (bits_per_sample) {
+    case 8:
+      return SND_PCM_FORMAT_U8;
+    case 16:
+      return SND_PCM_FORMAT_S16;
+    case 24:
+      return SND_PCM_FORMAT_S24;
+    case 32:
+      return SND_PCM_FORMAT_S32;
+    default:
+      return SND_PCM_FORMAT_UNKNOWN;
+  }
+}
+
 }  // namespace media