fallback to null sink in WebAudioSourceProvider::Initialize() + UMA stats for device status

media/base/output_device_info.h

Index: media/base/output_device_info.h
diff --git a/media/base/output_device_info.h b/media/base/output_device_info.h
index 9f90fed74f213f858fff0768140d81726a816266..96469d556bb19e07d3bd7002daa17b8832a96bf1 100644
--- a/media/base/output_device_info.h
+++ b/media/base/output_device_info.h
@@ -20,7 +20,10 @@ enum OutputDeviceStatus {
   OUTPUT_DEVICE_STATUS_ERROR_NOT_AUTHORIZED,
   OUTPUT_DEVICE_STATUS_ERROR_TIMED_OUT,
   OUTPUT_DEVICE_STATUS_ERROR_INTERNAL,
-  OUTPUT_DEVICE_STATUS_LAST = OUTPUT_DEVICE_STATUS_ERROR_INTERNAL,
+  // Add new values only above this line; do not changes existing values. Make
+  // sure OutputDeviceStatus enum in histoframs.xml is updated with any change
+  // here.
+  OUTPUT_DEVICE_STATUS_MAX = OUTPUT_DEVICE_STATUS_ERROR_INTERNAL
 };
 
 using OutputDeviceStatusCB = base::Callback<void(OutputDeviceStatus)>;