Add bluetooth discoverable footer preference in connected devices page

* For fix the TreeHugger error in pi-dev, cherry pick the ag/4042014 in
  master and fix TreeHugger error. Change android.support.v7.* to androidx.*
* Dynamicly add preference in controller
* Add test cases for DiscoverableFooterPreferenceController

Bug: 79294219
Test: make -j50 RunSettingsRoboTests
Change-Id: Id4c1e86c9a0a0cd69d8106a18f2cf4a0fa31782b

src/com/android/settings/connecteddevice/DiscoverableFooterPreferenceController.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2018 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.connecteddevice;
+
+import android.content.Context;
+import android.content.pm.PackageManager;
+import androidx.annotation.VisibleForTesting;
+import androidx.preference.PreferenceScreen;
+import com.android.settings.core.BasePreferenceController;
+import com.android.settings.dashboard.DashboardFragment;
+import com.android.settingslib.widget.FooterPreference;
+import com.android.settingslib.widget.FooterPreferenceMixin;
+
+/**
+ * Controller that shows and updates the bluetooth device name
+ */
+public class DiscoverableFooterPreferenceController extends BasePreferenceController {
+    private static final String KEY = "discoverable_footer_preference";
+
+    private FooterPreference mPreference;
+    private FooterPreferenceMixin mFooterPreferenceMixin;
+
+
+    public DiscoverableFooterPreferenceController(Context context) { super(context, KEY); }
+
+    public void init(DashboardFragment fragment) {
+        mFooterPreferenceMixin = new FooterPreferenceMixin(fragment, fragment.getLifecycle());
+    }
+
+    @VisibleForTesting
+    void init(FooterPreferenceMixin footerPreferenceMixin, FooterPreference preference) {
+        mFooterPreferenceMixin = footerPreferenceMixin;
+        mPreference = preference;
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        addFooterPreference(screen);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return mContext.getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH)
+                ? AVAILABLE
+                : UNSUPPORTED_ON_DEVICE;
+    }
+
+    private void addFooterPreference(PreferenceScreen screen) {
+        mPreference = mFooterPreferenceMixin.createFooterPreference();
+        mPreference.setKey(KEY);
+        screen.addPreference(mPreference);
+    }
+}