Add preference group for saved devcies.

Currently it only contains bluetooth devices.

Bug: 3240835
Test: RunSettingsRoboTests
Change-Id: Ief102e7174a4c4610dbda6b728419b303ff928f9

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

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.settings.bluetooth;
+
+import android.bluetooth.BluetoothAdapter;
+import android.bluetooth.BluetoothDevice;
+import android.support.annotation.VisibleForTesting;
+
+import com.android.settings.connecteddevice.DevicePreferenceCallback;
+import com.android.settings.dashboard.DashboardFragment;
+import com.android.settingslib.bluetooth.CachedBluetoothDevice;
+import com.android.settingslib.bluetooth.LocalBluetoothManager;
+
+/**
+ * Maintain and update saved bluetooth devices(bonded but not connected)
+ */
+public class SavedBluetoothDeviceUpdater extends BluetoothDeviceUpdater {
+
+    public SavedBluetoothDeviceUpdater(DashboardFragment fragment,
+            DevicePreferenceCallback devicePreferenceCallback) {
+        super(fragment, devicePreferenceCallback);
+    }
+
+    @VisibleForTesting
+    SavedBluetoothDeviceUpdater(DashboardFragment fragment,
+            DevicePreferenceCallback devicePreferenceCallback,
+            LocalBluetoothManager localBluetoothManager) {
+        super(fragment, devicePreferenceCallback, localBluetoothManager);
+    }
+
+    @Override
+    public void onConnectionStateChanged(CachedBluetoothDevice cachedDevice, int state) {
+        if (state == BluetoothAdapter.STATE_CONNECTED) {
+            removePreference(cachedDevice);
+        } else if (state == BluetoothAdapter.STATE_DISCONNECTED) {
+            addPreference(cachedDevice);
+        }
+    }
+
+    @Override
+    public boolean isFilterMatched(CachedBluetoothDevice cachedDevice) {
+        final BluetoothDevice device = cachedDevice.getDevice();
+        return device.getBondState() == BluetoothDevice.BOND_BONDED && !device.isConnected();
+    }
+}