Bluetooth: use TrackRecording handler for callback.

Otherwise the thread is not defined and a SecurityException may be triggered when inserting data into the ContentProvider.
Sadly, below API26 this needs to be done manually.

Fixes #1165.

src/main/java/de/dennisguse/opentracks/sensors/BluetoothConnectionManager.java

@@ -24,6 +24,8 @@ import android.bluetooth.BluetoothGattDescriptor;
 import android.bluetooth.BluetoothGattService;
 import android.bluetooth.BluetoothProfile;
 import android.content.Context;
+import android.os.Build;
+import android.os.Handler;
 import android.util.Log;
 
 import androidx.annotation.NonNull;
@@ -110,7 +112,12 @@ public abstract class BluetoothConnectionManager<DataType> {
             SensorData<DataType> sensorData = parsePayload(gatt.getDevice().getName(), gatt.getDevice().getAddress(), characteristic);
             if (sensorData != null) {
                 Log.d(TAG, "Decoded data from " + gatt.getDevice().getAddress() + ": " + sensorData);
-                observer.onChanged(sensorData);
+                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                    observer.onChanged(sensorData);
+                } else {
+                    //TODO This might lead to NPEs in case of race conditions due to shutdown.
+                    observer.getHandler().post(() -> observer.onChanged(sensorData));
+                }
             }
         }
     };
@@ -128,7 +135,11 @@ public abstract class BluetoothConnectionManager<DataType> {
 
         Log.d(TAG, "Connecting to: " + device);
 
-        bluetoothGatt = device.connectGatt(context, true, connectCallback);
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            bluetoothGatt = device.connectGatt(context, true, connectCallback, BluetoothDevice.TRANSPORT_AUTO, 0, this.observer.getHandler());
+        } else {
+            bluetoothGatt = device.connectGatt(context, true, connectCallback);
+        }
         SensorData<?> sensorData = createEmptySensorData(bluetoothGatt.getDevice().getAddress());
         observer.onChanged(sensorData);
     }
@@ -275,5 +286,8 @@ public abstract class BluetoothConnectionManager<DataType> {
         void onChanged(SensorData<?> sensorData);
 
         void onDisconnecting(SensorData<?> sensorData);
+
+        @NonNull
+        Handler getHandler();
     }
 }

src/main/java/de/dennisguse/opentracks/sensors/BluetoothRemoteSensorManager.java

@@ -20,6 +20,7 @@ import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.BluetoothDevice;
 import android.content.Context;
 import android.content.SharedPreferences;
+import android.os.Handler;
 import android.util.Log;
 
 import androidx.annotation.NonNull;
@@ -57,7 +58,7 @@ public class BluetoothRemoteSensorManager implements BluetoothConnectionManager.
 
     private final BluetoothAdapter bluetoothAdapter;
     private final Context context;
-
+    private final Handler handler;
     private boolean started = false;
 
     private Distance preferenceWheelCircumference;
@@ -111,8 +112,9 @@ public class BluetoothRemoteSensorManager implements BluetoothConnectionManager.
         }
     };
 
-    public BluetoothRemoteSensorManager(@NonNull Context context, @NonNull SensorDataSetChangeObserver observer) {
+    public BluetoothRemoteSensorManager(@NonNull Context context, @NonNull Handler handler, @NonNull SensorDataSetChangeObserver observer) {
         this.context = context;
+        this.handler = handler;
         this.observer = observer;
         bluetoothAdapter = BluetoothUtils.getAdapter(context);
     }
@@ -218,6 +220,12 @@ public class BluetoothRemoteSensorManager implements BluetoothConnectionManager.
         sensorDataSet.remove(sensorData);
     }
 
+    @NonNull
+    @Override
+    public Handler getHandler() {
+        return handler;
+    }
+
     public interface SensorDataSetChangeObserver {
         void onChange(SensorDataSet sensorDataSet);
     }

src/main/java/de/dennisguse/opentracks/services/TrackRecordingService.java

@@ -211,7 +211,7 @@ public class TrackRecordingService extends Service implements TrackPointCreator.
 
     private void startSensors() {
         wakeLock = SystemUtils.acquireWakeLock(this, wakeLock);
-        trackPointCreator.start(this);
+        trackPointCreator.start(this, handler);
         showNotification(true);
     }
 

src/main/java/de/dennisguse/opentracks/services/handlers/TrackPointCreator.java

@@ -2,6 +2,7 @@ package de.dennisguse.opentracks.services.handlers;
 
 import android.content.Context;
 import android.location.Location;
+import android.os.Handler;
 import android.util.Log;
 import android.util.Pair;
 
@@ -48,12 +49,12 @@ public class TrackPointCreator implements BluetoothRemoteSensorManager.SensorDat
         this.gpsHandler = gpsHandler;
     }
 
-    public synchronized void start(@NonNull Context context) {
+    public synchronized void start(@NonNull Context context, @NonNull Handler handler) {
         this.context = context;
 
         gpsHandler.onStart(context);
 
-        remoteSensorManager = new BluetoothRemoteSensorManager(context, this);
+        remoteSensorManager = new BluetoothRemoteSensorManager(context, handler, this);
         altitudeSumManager = new AltitudeSumManager();
 
         remoteSensorManager.start();