Decouple BluetoothDevicePreference and DeviceListPreferenceFragment

The BluetoothDevicePreference need to know whether to display with an
invalid name. However pass in the whole fragment is over-killing.

This cl decouple it for several reasons:
1. In P, BluetoothDevicePreference will be used in other fragment.
2. In preference lifecycle from end user side, this flag is constant.

Bug: 69333961
Test: RunSettingsRoboTests
Change-Id: I3dbcd2a4aafa3ead74371534250e5e7c3ee221f7

src/com/android/settings/bluetooth/DeviceListPreferenceFragment.java

@@ -98,6 +98,8 @@ public abstract class DeviceListPreferenceFragment extends
             return;
         }
         mLocalAdapter = mLocalManager.getBluetoothAdapter();
+        mShowDevicesWithoutNames = SystemProperties.getBoolean(
+                BLUETOOTH_SHOW_DEVICES_WITHOUT_NAMES_PROPERTY, false);
 
         initPreferencesFromPreferenceScreen();
 
@@ -110,8 +112,6 @@ public abstract class DeviceListPreferenceFragment extends
     @Override
     public void onStart() {
         super.onStart();
-        mShowDevicesWithoutNames = SystemProperties.getBoolean(
-                BLUETOOTH_SHOW_DEVICES_WITHOUT_NAMES_PROPERTY, false);
         if (mLocalManager == null || isUiRestricted()) return;
 
         mLocalManager.setForegroundActivity(getActivity());
@@ -190,7 +190,8 @@ public abstract class DeviceListPreferenceFragment extends
         BluetoothDevicePreference preference = (BluetoothDevicePreference) getCachedPreference(key);
 
         if (preference == null) {
-            preference = new BluetoothDevicePreference(getPrefContext(), cachedDevice, this);
+            preference = new BluetoothDevicePreference(getPrefContext(), cachedDevice,
+                    mShowDevicesWithoutNames);
             preference.setKey(key);
             mDeviceListGroup.addPreference(preference);
         } else {