[Provider Model] Implement the carrner network selection settings

- Add WifiPickerTrackerHelper to reuse the library

- User taps on carrier network preference
  - Calls MergedCarrierEntry#connect()

- User toggles mobile data On/Off
  - Calls MergedCarrierEntry#setEnabled(true/false)

Bug: 175761096
Test:
- Manual Test
- atest NetworkMobileProviderControllerTest \
        SubscriptionsPreferenceControllerTest \
        WifiPickerTrackerHelperTest

Change-Id: Ia311b10ca7a44a536556c1889ee65743af379822

src/com/android/settings/wifi/WifiPickerTrackerHelper.java

@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2021 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.wifi;
+
+import android.content.Context;
+import android.net.ConnectivityManager;
+import android.net.NetworkScoreManager;
+import android.net.wifi.WifiManager;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.Looper;
+import android.os.Process;
+import android.os.SimpleClock;
+import android.os.SystemClock;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.lifecycle.Lifecycle;
+import androidx.lifecycle.LifecycleObserver;
+import androidx.lifecycle.OnLifecycleEvent;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.wifitrackerlib.MergedCarrierEntry;
+import com.android.wifitrackerlib.WifiEntry;
+import com.android.wifitrackerlib.WifiPickerTracker;
+
+import java.time.Clock;
+import java.time.ZoneOffset;
+
+public class WifiPickerTrackerHelper implements LifecycleObserver {
+
+    private static final String TAG = "WifiPickerTrackerHelper";
+
+    // Max age of tracked WifiEntries
+    private static final long MAX_SCAN_AGE_MILLIS = 15_000;
+    // Interval between initiating WifiPickerTracker scans
+    private static final long SCAN_INTERVAL_MILLIS = 10_000;
+    // Clock used for evaluating the age of scans
+    private static final Clock ELAPSED_REALTIME_CLOCK = new SimpleClock(ZoneOffset.UTC) {
+        @Override
+        public long millis() {
+            return SystemClock.elapsedRealtime();
+        }
+    };
+
+    private WifiPickerTracker mWifiPickerTracker;
+    // Worker thread used for WifiPickerTracker work
+    private HandlerThread mWorkerThread;
+
+    public WifiPickerTrackerHelper(@NonNull Lifecycle lifecycle, @NonNull Context context,
+            @Nullable WifiPickerTracker.WifiPickerTrackerCallback listener) {
+        if (lifecycle == null) {
+            throw new IllegalArgumentException("lifecycle must be non-null.");
+        }
+        lifecycle.addObserver(this);
+        mWorkerThread = new HandlerThread(TAG
+                + "{" + Integer.toHexString(System.identityHashCode(this)) + "}",
+                Process.THREAD_PRIORITY_BACKGROUND);
+        mWorkerThread.start();
+
+        mWifiPickerTracker = new WifiPickerTracker(lifecycle, context,
+                context.getSystemService(WifiManager.class),
+                context.getSystemService(ConnectivityManager.class),
+                context.getSystemService(NetworkScoreManager.class),
+                new Handler(Looper.getMainLooper()),
+                mWorkerThread.getThreadHandler(),
+                ELAPSED_REALTIME_CLOCK,
+                MAX_SCAN_AGE_MILLIS,
+                SCAN_INTERVAL_MILLIS,
+                listener);
+    }
+
+    @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
+    public void onDestroy() {
+        mWorkerThread.quit();
+    }
+
+    public @NonNull WifiPickerTracker getWifiPickerTracker() {
+        return mWifiPickerTracker;
+    }
+
+    public boolean setCarrierNetworkEnabled(boolean enable) {
+        final MergedCarrierEntry mergedCarrierEntry = mWifiPickerTracker.getMergedCarrierEntry();
+        if (mergedCarrierEntry == null) {
+            return false;
+        }
+        mergedCarrierEntry.setEnabled(enable);
+        return true;
+    }
+
+    public boolean connectCarrierNetwork(@Nullable WifiEntry.ConnectCallback callback) {
+        final MergedCarrierEntry mergedCarrierEntry = mWifiPickerTracker.getMergedCarrierEntry();
+        if (mergedCarrierEntry == null || !mergedCarrierEntry.canConnect()) {
+            return false;
+        }
+        mergedCarrierEntry.connect(callback);
+        return true;
+    }
+
+    @VisibleForTesting
+    void setWifiPickerTracker(@NonNull WifiPickerTracker wifiPickerTracker) {
+        mWifiPickerTracker = wifiPickerTracker;
+    }
+
+    @VisibleForTesting
+    void setWorkerThread(@NonNull HandlerThread workerThread) {
+        mWorkerThread = workerThread;
+    }
+}