Bluetooth: Only show devices when their names are resolved

* Add a developer menu option to allow name-less devices to be shown
  when a Bluetooth developer needs it, but hide it for non-developer
  users.
* Set BluetoothDevicePreference to invisible when CachedBluetoothDevice
  does not have a name besides MAC address and the above developer option
  is false.
* This affects BluetoothPairingDetail and DevicePickerFragment, but does
  not affect BluetoothSettings. BluetoothSettings will show all paired
  devices regardless whether an user friendly name exists.

Bug: 34685932
Test: pair Bluetooth device, send file over Bluetooth, unit tests
Change-Id: Idd7ad4b1671dfdcf3204efb50eddb6dae1065aa5

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

@@ -54,16 +54,17 @@ public final class BluetoothDevicePreference extends GearPreference implements
     private final UserManager mUserManager;
 
     private AlertDialog mDisconnectDialog;
-
     private String contentDescription = null;
-
+    private DeviceListPreferenceFragment mDeviceListPreferenceFragment;
     /* Talk-back descriptions for various BT icons */
     Resources mResources;
 
-    public BluetoothDevicePreference(Context context, CachedBluetoothDevice cachedDevice) {
+    public BluetoothDevicePreference(Context context, CachedBluetoothDevice cachedDevice,
+            DeviceListPreferenceFragment deviceListPreferenceFragment) {
         super(context, null);
         mResources = getContext().getResources();
         mUserManager = (UserManager) context.getSystemService(Context.USER_SERVICE);
+        mDeviceListPreferenceFragment = deviceListPreferenceFragment;
 
         if (sDimAlpha == Integer.MIN_VALUE) {
             TypedValue outValue = new TypedValue();
@@ -131,6 +132,11 @@ public final class BluetoothDevicePreference extends GearPreference implements
         // Used to gray out the item
         setEnabled(!mCachedDevice.isBusy());
 
+        // Device is only visible in the UI if it has a valid name besides MAC address or when user
+        // allows showing devices without user-friendly name in developer settings
+        setVisible(mDeviceListPreferenceFragment.shouldShowDevicesWithoutNames()
+                || mCachedDevice.hasHumanReadableName());
+
         // This could affect ordering, so notify that
         notifyHierarchyChanged();
     }