le_audio: Introduce Unicast fallback after Broadcast stop

This change introduces support for fallback to Unicast streaming once
Broadcast streaming is finished. To make this happend Broadcast needs to
expropriate Unicast stream then this Broadcast needs to be stopped.

Tag: #feature
Bug: 294513510
Test: atest LeAudioServiceTest
Change-Id: I2cdd8f2576b2a1bdd30e1c8fd8cff870cd4be552

android/app/src/com/android/bluetooth/le_audio/LeAudioService.java

@@ -139,6 +139,7 @@ public class LeAudioService extends ProfileService {
     AudioManager mAudioManager;
     LeAudioTmapGattServer mTmapGattServer;
     int mTmapRoleMask;
+    int mUnicastGroupIdDeactivatedForBroadcastTransition = LE_AUDIO_GROUP_ID_INVALID;
     boolean mTmapStarted = false;
     private boolean mAwaitingBroadcastCreateResponse = false;
     private final LinkedList<BluetoothLeBroadcastSettings> mCreateBroadcastQueue =
@@ -1902,6 +1903,28 @@ public class LeAudioService extends ProfileService {
         }
     }
 
+    void transitionFromBroadcastToUnicast() {
+        BluetoothDevice unicastDevice =
+                getLeadDeviceForTheGroup(mUnicastGroupIdDeactivatedForBroadcastTransition);
+        if (unicastDevice == null) {
+            Log.e(TAG, "EVENT_TYPE_BROADCAST_DESTROYED: No valid unicast device for group ID: "
+                    + mUnicastGroupIdDeactivatedForBroadcastTransition);
+            mUnicastGroupIdDeactivatedForBroadcastTransition = LE_AUDIO_GROUP_ID_INVALID;
+            return;
+        }
+
+        if (DBG) {
+            Log.d(TAG, "Transitionaing to Unicast stream for group: "
+                    + mUnicastGroupIdDeactivatedForBroadcastTransition
+                    + ", with device: "
+                    + unicastDevice);
+        }
+
+        mUnicastGroupIdDeactivatedForBroadcastTransition = LE_AUDIO_GROUP_ID_INVALID;
+
+        setActiveDevice(unicastDevice);
+    }
+
     // Suppressed since this is part of a local process
     @SuppressLint("AndroidFrameworkRequiresPermission")
     void messageFromNative(LeAudioStackEvent stackEvent) {
@@ -2089,6 +2112,7 @@ public class LeAudioService extends ProfileService {
                     handleGroupTransitToInactive(groupId, false);
 
                     if (!mCreateBroadcastQueue.isEmpty()) {
+                        mUnicastGroupIdDeactivatedForBroadcastTransition = groupId;
                         BluetoothLeBroadcastSettings settings = mCreateBroadcastQueue.remove();
                         createBroadcast(settings);
                     }
@@ -2146,6 +2170,11 @@ public class LeAudioService extends ProfileService {
             }
             mBroadcastDescriptors.remove(broadcastId);
 
+            /* Restore the Unicast stream from before the Broadcast was started. */
+            if (mUnicastGroupIdDeactivatedForBroadcastTransition != LE_AUDIO_GROUP_ID_INVALID) {
+                transitionFromBroadcastToUnicast();
+            }
+
         } else if (stackEvent.type == LeAudioStackEvent.EVENT_TYPE_BROADCAST_STATE) {
             int broadcastId = stackEvent.valueInt1;
             int state = stackEvent.valueInt2;
@@ -2933,6 +2962,10 @@ public class LeAudioService extends ProfileService {
                     handleGroupTransitToInactive(groupId, false);
                 }
                 mGroupDescriptors.remove(groupId);
+
+                if (mUnicastGroupIdDeactivatedForBroadcastTransition == groupId) {
+                    mUnicastGroupIdDeactivatedForBroadcastTransition = LE_AUDIO_GROUP_ID_INVALID;
+                }
             }
             notifyGroupNodeRemoved(device, groupId);
         }
@@ -3937,6 +3970,8 @@ public class LeAudioService extends ProfileService {
         ProfileService.println(sb, "  currentlyActiveGroupId: " + getActiveGroupId());
         ProfileService.println(sb, "  mActiveAudioOutDevice: " + mActiveAudioOutDevice);
         ProfileService.println(sb, "  mActiveAudioInDevice: " + mActiveAudioInDevice);
+        ProfileService.println(sb, "  mUnicastGroupIdDeactivatedForBroadcastTransition: "
+                + mUnicastGroupIdDeactivatedForBroadcastTransition);
         ProfileService.println(sb, "  mExposedActiveDevice: " + mExposedActiveDevice);
         ProfileService.println(sb, "  mHfpHandoverDevice:" + mHfpHandoverDevice);
         ProfileService.println(sb, "  mLeAudioIsInbandRingtoneSupported:"