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

ash/system/tray/default_system_tray_delegate.cc

Index: ash/system/tray/default_system_tray_delegate.cc
diff --git a/ash/system/tray/default_system_tray_delegate.cc b/ash/system/tray/default_system_tray_delegate.cc
index 46c4c3d24d1d6097bf3b605bf5c890fcb40ad5e2..694b66bcaadf1bb3f0250b20142681030e788f32 100644
--- a/ash/system/tray/default_system_tray_delegate.cc
+++ b/ash/system/tray/default_system_tray_delegate.cc
@@ -253,6 +253,10 @@ bool DefaultSystemTrayDelegate::GetBluetoothEnabled() {
   return bluetooth_enabled_;
 }
 
+bool DefaultSystemTrayDelegate::GetBluetoothDiscovering() {
+  return false;
+}
+
 void DefaultSystemTrayDelegate::ChangeProxySettings() {
 }