Use getPrivateDnsMode() to get the value of private DNS

PRIVATE_DNS_DEFAULT_MODE_FALLBACK has removed, use
ConnectivityManager#getPrivateDnsMode() to get the value of
private DNS instead of querying settings and implementing logic
by itself.

Bug: 172183305
Test: make RunSettingsRoboTests \
      ROBOTEST_FILTER=PrivateDnsPreferenceControllerTest
Test: make RunSettingsRoboTests \
      ROBOTEST_FILTER=PrivateDnsModeDialogPreferenceTest
Change-Id: I024c3ddfb85f4c3d177e2e99294c998d81d4e08d
Merged-In: I024c3ddfb85f4c3d177e2e99294c998d81d4e08d
diff --git a/src/com/android/settings/network/PrivateDnsModeDialogPreference.java b/src/com/android/settings/network/PrivateDnsModeDialogPreference.java
index 4878f31..ea29a1d 100644
--- a/src/com/android/settings/network/PrivateDnsModeDialogPreference.java
+++ b/src/com/android/settings/network/PrivateDnsModeDialogPreference.java
@@ -15,7 +15,6 @@
  */
 package com.android.settings.network;
 
-import static android.net.ConnectivityManager.PRIVATE_DNS_DEFAULT_MODE_FALLBACK;
 import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_OFF;
 import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_OPPORTUNISTIC;
 import static android.net.ConnectivityManager.PRIVATE_DNS_MODE_PROVIDER_HOSTNAME;
@@ -28,6 +27,7 @@
 import android.content.Context;
 import android.content.DialogInterface;
 import android.content.Intent;
+import android.net.ConnectivityManager;
 import android.os.UserHandle;
 import android.os.UserManager;
 import android.provider.Settings;
@@ -84,14 +84,6 @@
     @VisibleForTesting
     static final String HOSTNAME_KEY = Settings.Global.PRIVATE_DNS_SPECIFIER;
 
-    public static String getModeFromSettings(ContentResolver cr) {
-        String mode = Settings.Global.getString(cr, MODE_KEY);
-        if (!PRIVATE_DNS_MAP.containsKey(mode)) {
-            mode = Settings.Global.getString(cr, Settings.Global.PRIVATE_DNS_DEFAULT_MODE);
-        }
-        return PRIVATE_DNS_MAP.containsKey(mode) ? mode : PRIVATE_DNS_DEFAULT_MODE_FALLBACK;
-    }
-
     public static String getHostnameFromSettings(ContentResolver cr) {
         return Settings.Global.getString(cr, HOSTNAME_KEY);
     }
@@ -168,7 +160,7 @@
         final Context context = getContext();
         final ContentResolver contentResolver = context.getContentResolver();
 
-        mMode = getModeFromSettings(context.getContentResolver());
+        mMode = ConnectivityManager.getPrivateDnsMode(contentResolver);
 
         mEditText = view.findViewById(R.id.private_dns_mode_provider_hostname);
         mEditText.addTextChangedListener(this);
diff --git a/src/com/android/settings/network/PrivateDnsPreferenceController.java b/src/com/android/settings/network/PrivateDnsPreferenceController.java
index 84cae88..3136040 100644
--- a/src/com/android/settings/network/PrivateDnsPreferenceController.java
+++ b/src/com/android/settings/network/PrivateDnsPreferenceController.java
@@ -118,7 +118,7 @@
     public CharSequence getSummary() {
         final Resources res = mContext.getResources();
         final ContentResolver cr = mContext.getContentResolver();
-        final String mode = PrivateDnsModeDialogPreference.getModeFromSettings(cr);
+        final String mode = ConnectivityManager.getPrivateDnsMode(cr);
         final LinkProperties lp = mLatestLinkProperties;
         final List<InetAddress> dnses = (lp == null) ? null : lp.getValidatedPrivateDnsServers();
         final boolean dnsesResolved = !ArrayUtils.isEmpty(dnses);