Cache routed device in case returning null when switching device.

Bug: 69366408
Test: runtest --path cts/tests/tests/media/src/android/media/cts/RoutingTest.java
Change-Id: I270fe60abdf22eada927bf0c5fc594de294c8428
diff --git a/media/libmediaplayerservice/MediaPlayerService.h b/media/libmediaplayerservice/MediaPlayerService.h
index 71e87a0..eefdd7d 100644
--- a/media/libmediaplayerservice/MediaPlayerService.h
+++ b/media/libmediaplayerservice/MediaPlayerService.h
@@ -176,6 +176,7 @@
         audio_output_flags_t    mFlags;
         sp<media::VolumeHandler>       mVolumeHandler;
         audio_port_handle_t     mSelectedDeviceId;
+        audio_port_handle_t     mRoutedDeviceId;
         bool                    mDeviceCallbackEnabled;
         wp<AudioSystem::AudioDeviceCallback>        mDeviceCallback;
         mutable Mutex           mLock;