Persist the user's active audio device choice across chromeos session and reboots.

extensions/shell/browser/shell_audio_controller_chromeos.cc

Index: extensions/shell/browser/shell_audio_controller_chromeos.cc
diff --git a/extensions/shell/browser/shell_audio_controller_chromeos.cc b/extensions/shell/browser/shell_audio_controller_chromeos.cc
index 19e34ce291df058a01a1c162a95fb91f9c10519b..1e89065861b27b7ecaa7c86afd088b541466fa77 100644
--- a/extensions/shell/browser/shell_audio_controller_chromeos.cc
+++ b/extensions/shell/browser/shell_audio_controller_chromeos.cc
@@ -78,13 +78,15 @@ void ShellAudioController::ActivateDevices() {
     const chromeos::AudioDevice* device = GetDevice(devices, best_input);
     DCHECK(device);
     VLOG(1) << "Activating input device: " << device->ToString();
-    handler->SwitchToDevice(*device, true);
+    handler->SwitchToDevice(*device, true,
+                            chromeos::CrasAudioHandler::ACTIVATE_BY_USER);
   }
   if (best_output && best_output != handler->GetPrimaryActiveOutputNode()) {
     const chromeos::AudioDevice* device = GetDevice(devices, best_output);
     DCHECK(device);
     VLOG(1) << "Activating output device: " << device->ToString();
-    handler->SwitchToDevice(*device, true);
+    handler->SwitchToDevice(*device, true,
+                            chromeos::CrasAudioHandler::ACTIVATE_BY_USER);
   }
 }