Settings: Add switch preference for AGPS

Allow toggling AGPS (which in turn disables SUPL) using the existing
AOSP mechanism that was simply never exposed to the user.
Based on the following commits from CodeAurora, modified to
use SwitchPreference and improved strings:

Author: juwei <juwei@codeaurora.org>
Date:   Mon May 7 13:31:50 2018 +0800
    Settings: Add AGPS setting menu.

    Add AGPS setting switch to allow user turn on/off
    AGPS function.

    Change-Id: If8a20a8293b9f4b12933bc3820b4cd135a938b72
    CRs-Fixed: 2169854

Author: hoffc <hoffc@codeaurora.org>
Date:   Wed Dec 19 15:56:07 2018 +0800
    Settings: Refactor Agps preference controller code

    (1) Extract inner class AgpsPreferenceController as one standalone file.
    (2) Delete the useless code of reading the SUPL server and port from etc/gps.conf file.
    (3) Remove the config item "config_agps_enabled".

    Change-Id: I20465aa4375c7fe64bc84f579a39178506b8e211
    CRs-Fixed: 2370304

Author: hoffc <hoffc@codeaurora.org>
Date:   Tue Jun 1 08:52:31 2021 +0800
    Settings: fix NPE caused by missing agps preference definition

    No agps preference is defined in location settings, results in NPE when agps controller init

    add agps preference definition in location settings

    Change-Id: I92e3293bccb90da7b6a1057e2dd83f8aa909d308
    CRs-Fixed: 2958241

Issue: calyxos#1490
Co-authored-by: Chirayu Desai <chirayudesai1@gmail.com>
Co-authored-by: Michael Bestas <mkbestas@lineageos.org>
Change-Id: Idea7026f0c954c1f2a056e7b4595a879ef161f5c

res/values/cm_strings.xml

@@ -140,4 +140,9 @@
 
     <!-- Warning message for the sd card setup -->
     <string name="storage_warning_internal">Warning: This option may not work properly or lead to data loss and is therefore not recommended!</string>
+
+    <!-- Location settings screen, setting check box label if Assisted GPS should be enabled -->
+    <string name="assisted_gps">Use assisted GPS</string>
+    <!-- Location settings screen, setting summary for Assisted GPS switch -->
+    <string name="assisted_gps_summary">Download satellite assistance data from the internet which can greatly improve the GPS startup performance. For emergency calls, assisted GPS is always allowed.</string>
 </resources>

res/xml/location_settings.xml

@@ -35,6 +35,12 @@
         settings:controller="com.android.settings.location.RecentLocationAccessSeeAllButtonPreferenceController"
         settings:searchable="false"/>
 
+    <SwitchPreferenceCompat
+        android:key="assisted_gps"
+        android:title="@string/assisted_gps"
+        android:summary="@string/assisted_gps_summary"
+        settings:controller="com.android.settings.location.AgpsPreferenceController"/>
+
     <PreferenceCategory
         android:key="location_advanced_settings"
         android:layout="@layout/preference_category_no_label">

src/com/android/settings/location/AgpsPreferenceController.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2011 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.location;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.provider.Settings;
+
+import androidx.preference.SwitchPreferenceCompat;
+import androidx.preference.Preference;
+import androidx.preference.PreferenceScreen;
+
+public class AgpsPreferenceController extends LocationBasePreferenceController {
+    private static final String KEY_ASSISTED_GPS = "assisted_gps";
+
+    private SwitchPreferenceCompat mAgpsPreference;
+
+    public AgpsPreferenceController(Context context, String key) {
+        super(context, key);
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return KEY_ASSISTED_GPS;
+    }
+
+    @AvailabilityStatus
+    public int getAvailabilityStatus() {
+        return AVAILABLE;
+    }
+
+    @Override
+    public void displayPreference(PreferenceScreen screen) {
+        super.displayPreference(screen);
+        mAgpsPreference = (SwitchPreferenceCompat) screen.findPreference(KEY_ASSISTED_GPS);
+    }
+
+    @Override
+    public void updateState(Preference preference) {
+        if (mAgpsPreference != null) {
+            mAgpsPreference.setChecked(Settings.Global.getInt(
+                    mContext.getContentResolver(), Settings.Global.ASSISTED_GPS_ENABLED, 1) == 1);
+        }
+    }
+
+    @Override
+    public boolean handlePreferenceTreeClick(Preference preference) {
+        if (KEY_ASSISTED_GPS.equals(preference.getKey())) {
+            final ContentResolver cr = mContext.getContentResolver();
+            final boolean switchState = mAgpsPreference.isChecked();
+            Settings.Global.putInt(cr, Settings.Global.ASSISTED_GPS_ENABLED,
+                    switchState ? 1 : 0);
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public void onLocationModeChanged(int mode, boolean restricted) {}
+}

src/com/android/settings/location/LocationSettings.java

@@ -122,6 +122,7 @@ public class LocationSettings extends DashboardFragment implements
         use(LocationForWorkPreferenceController.class).init(this);
         use(LocationSettingsFooterPreferenceController.class).init(this);
         use(LocationForPrivateProfilePreferenceController.class).init(this);
+        use(AgpsPreferenceController.class).init(this);
     }
 
     @Override