Add wifi metered controls in wifi settings.

1. Add it in wifi detail page
2. Add it in wifi dialog
2. Remove it in "Mobile network" page

Bug: 68030417
Test: RunSettingsRoboTests
Change-Id: I2e001c55f3c6c75a660e429732dfbece97b0ca9e

src/com/android/settings/wifi/details/WifiMeteredPreferenceController.java

@@ -0,0 +1,83 @@
+/*
+ * 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.wifi.details;
+
+import android.app.backup.BackupManager;
+import android.content.Context;
+import android.net.wifi.WifiConfiguration;
+import android.net.wifi.WifiManager;
+import android.provider.Settings;
+import android.support.annotation.VisibleForTesting;
+import android.support.v14.preference.SwitchPreference;
+import android.support.v7.preference.DropDownPreference;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceScreen;
+import android.text.TextUtils;
+
+import com.android.settings.core.BasePreferenceController;
+import com.android.settings.core.PreferenceControllerMixin;
+import com.android.settingslib.core.AbstractPreferenceController;
+
+/**
+ * {@link AbstractPreferenceController} that controls whether the wifi network is metered or not
+ */
+public class WifiMeteredPreferenceController extends BasePreferenceController implements
+        Preference.OnPreferenceChangeListener {
+
+    private static final String KEY_WIFI_METERED = "metered";
+    private WifiConfiguration mWifiConfiguration;
+    private WifiManager mWifiManager;
+
+    public WifiMeteredPreferenceController(Context context, WifiConfiguration wifiConfiguration) {
+        super(context, KEY_WIFI_METERED);
+        mWifiConfiguration = wifiConfiguration;
+        mWifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        final DropDownPreference dropDownPreference = (DropDownPreference) preference;
+        final int meteredOverride = getMeteredOverride();
+        dropDownPreference.setValue(Integer.toString(meteredOverride));
+        updateSummary(dropDownPreference, meteredOverride);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return AVAILABLE;
+    }
+
+    @Override
+    public boolean onPreferenceChange(Preference preference, Object newValue) {
+        mWifiConfiguration.meteredOverride = Integer.parseInt((String) newValue);
+        mWifiManager.updateNetwork(mWifiConfiguration);
+        // Stage the backup of the SettingsProvider package which backs this up
+        BackupManager.dataChanged("com.android.providers.settings");
+        updateSummary((DropDownPreference) preference, getMeteredOverride());
+        return true;
+    }
+
+    @VisibleForTesting
+    int getMeteredOverride() {
+        // Wrap the meteredOverride since robolectric cannot recognize it
+        return mWifiConfiguration.meteredOverride;
+    }
+
+    private void updateSummary(DropDownPreference preference, int meteredOverride) {
+        preference.setSummary(preference.getEntries()[meteredOverride]);
+    }
+}