ash::internal::TrayBluetooth: Hide spinner if discovery session stops.

ash/system/tray/system_tray_delegate.h

Index: ash/system/tray/system_tray_delegate.h
diff --git a/ash/system/tray/system_tray_delegate.h b/ash/system/tray/system_tray_delegate.h
index 67d1f8cf32bc0a917ce0f77d2f37ae99b7e102f4..fe0863bc4e100421cc96cc0950a4b15791ee8775 100644
--- a/ash/system/tray/system_tray_delegate.h
+++ b/ash/system/tray/system_tray_delegate.h
@@ -300,6 +300,9 @@ class ASH_EXPORT SystemTrayDelegate {
   // Returns whether bluetooth is enabled.
   virtual bool GetBluetoothEnabled() = 0;
 
+  // Returns whether the delegate has initiated a bluetooth discovery session.
+  virtual bool GetBluetoothDiscovering() = 0;
+
   // Shows UI for changing proxy settings.
   virtual void ChangeProxySettings() = 0;