Add preference group for saved devcies.

Currently it only contains bluetooth devices.

Bug: 3240835
Test: RunSettingsRoboTests
Change-Id: Ief102e7174a4c4610dbda6b728419b303ff928f9

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

@@ -148,10 +148,23 @@ public abstract class BluetoothDeviceUpdater implements BluetoothCallback {
         mPrefContext = context;
     }
 
+    /**
+     * Return {@code true} if {@code cachedBluetoothDevice} matches this
+     * {@link BluetoothDeviceUpdater} and should stay in the list, otherwise return {@code false}
+     */
+    public abstract boolean isFilterMatched(CachedBluetoothDevice cachedBluetoothDevice);
+
     /**
      * Update whether to show {@cde cachedBluetoothDevice} in the list.
      */
-    abstract public void update(CachedBluetoothDevice cachedBluetoothDevice);
+    protected void update(CachedBluetoothDevice cachedBluetoothDevice) {
+        if (isFilterMatched(cachedBluetoothDevice)) {
+            // Add the preference if it is new one
+            addPreference(cachedBluetoothDevice);
+        } else {
+            removePreference(cachedBluetoothDevice);
+        }
+    }
 
     /**
      * Add the {@link Preference} that represents the {@code cachedDevice}

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

@@ -51,16 +51,8 @@ public class ConnectedBluetoothDeviceUpdater extends BluetoothDeviceUpdater {
     }
 
     @Override
-    public void update(CachedBluetoothDevice cachedDevice) {
+    public boolean isFilterMatched(CachedBluetoothDevice cachedDevice) {
         final BluetoothDevice device = cachedDevice.getDevice();
-        final boolean filterMatch =
-                device.getBondState() == BluetoothDevice.BOND_BONDED && device.isConnected();
-
-        if (filterMatch) {
-            // Add the preference if it is new one
-            addPreference(cachedDevice);
-        } else {
-            removePreference(cachedDevice);
-        }
+        return device.getBondState() == BluetoothDevice.BOND_BONDED && device.isConnected();
     }
 }

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();
+    }
+}