AS: use dock device for volume when dock device is selected.

Bug: 262415494
Test: make
Change-Id: I91447fbea6fbfe0e7f290f8832ac44dc71b60042
diff --git a/services/core/java/com/android/server/audio/AudioService.java b/services/core/java/com/android/server/audio/AudioService.java
index ac55f28..d1cbbfc 100644
--- a/services/core/java/com/android/server/audio/AudioService.java
+++ b/services/core/java/com/android/server/audio/AudioService.java
@@ -7053,13 +7053,16 @@
             return deviceSet.iterator().next();
         } else {
             // Multiple device selection is either:
+            //  - dock + one other device: give priority to dock in this case.
             //  - speaker + one other device: give priority to speaker in this case.
             //  - one A2DP device + another device: happens with duplicated output. In this case
             // retain the device on the A2DP output as the other must not correspond to an active
             // selection if not the speaker.
             //  - HDMI-CEC system audio mode only output: give priority to available item in order.
 
-            if (deviceSet.contains(AudioSystem.DEVICE_OUT_SPEAKER)) {
+            if (deviceSet.contains(AudioSystem.DEVICE_OUT_DGTL_DOCK_HEADSET)) {
+                return AudioSystem.DEVICE_OUT_DGTL_DOCK_HEADSET;
+            } else if (deviceSet.contains(AudioSystem.DEVICE_OUT_SPEAKER)) {
                 return AudioSystem.DEVICE_OUT_SPEAKER;
             } else if (deviceSet.contains(AudioSystem.DEVICE_OUT_SPEAKER_SAFE)) {
                 // Note: DEVICE_OUT_SPEAKER_SAFE not present in getDeviceSetForStreamDirect