Store audio device's active state in preference

chromeos/audio/audio_device.h

Index: chromeos/audio/audio_device.h
diff --git a/chromeos/audio/audio_device.h b/chromeos/audio/audio_device.h
index ee47ee5e2be0b6d0c790fff388526bbc1e21b1ee..7697dafceb5e5fd3bbe758388e7eb10dd29b92c4 100644
--- a/chromeos/audio/audio_device.h
+++ b/chromeos/audio/audio_device.h
@@ -58,6 +58,7 @@ struct CHROMEOS_EXPORT AudioDevice {
 
   bool is_input;
   uint64_t id;
+  uint64_t stable_device_id;

[Daniel Erat, 2016/01/07 17:31:12]

document the difference between this and id. why do we need both? is the plan to
eventually transition to just using one?

[hychao, 2016/01/11 07:02:32]

Done. Added comment to describe the two IDs. There is no plan to deprecate any
one of them, but expect them to be used in a mixed way for different scenario.

   std::string display_name;
   std::string device_name;
   std::string mic_positions;