Factor in PRIVATE_DNS_MODE_DEFAULTSETTING value

This setting can be used to change the in-code default.

Test: as follows
    - built, flashed, booted
    - make -j50 RunSettingsRoboTests ROBOTEST_FILTER=PrivateDnsModeDialogPreferenceTest passes
    - make -j50 RunSettingsRoboTests ROBOTEST_FILTER=PrivateDnsPreferenceControllerTest passes
Bug: 79719289
Change-Id: I27e5fb9cc66dde1df72395c22179bca3f62ef782

src/com/android/settings/network/PrivateDnsModeDialogPreference.java

@@ -15,6 +15,7 @@
  */
 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;
@@ -79,8 +80,11 @@ public class PrivateDnsModeDialogPreference extends CustomDialogPreference imple
     static final String HOSTNAME_KEY = Settings.Global.PRIVATE_DNS_SPECIFIER;
 
     public static String getModeFromSettings(ContentResolver cr) {
-        final String mode = Settings.Global.getString(cr, MODE_KEY);
+        String mode = Settings.Global.getString(cr, MODE_KEY);
-        return PRIVATE_DNS_MAP.containsKey(mode) ? mode : PRIVATE_DNS_MODE_OPPORTUNISTIC;
+        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) {

src/com/android/settings/network/PrivateDnsPreferenceController.java

@@ -19,6 +19,9 @@ package com.android.settings.network;
 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;
+import static android.provider.Settings.Global.PRIVATE_DNS_DEFAULT_MODE;
+import static android.provider.Settings.Global.PRIVATE_DNS_MODE;
+import static android.provider.Settings.Global.PRIVATE_DNS_SPECIFIER;
 
 import android.content.Context;
 import android.content.ContentResolver;
@@ -51,8 +54,9 @@ public class PrivateDnsPreferenceController extends BasePreferenceController
     private static final String KEY_PRIVATE_DNS_SETTINGS = "private_dns_settings";
 
     private static final Uri[] SETTINGS_URIS = new Uri[]{
-        Settings.Global.getUriFor(Settings.Global.PRIVATE_DNS_MODE),
+        Settings.Global.getUriFor(PRIVATE_DNS_MODE),
-        Settings.Global.getUriFor(Settings.Global.PRIVATE_DNS_SPECIFIER),
+        Settings.Global.getUriFor(PRIVATE_DNS_DEFAULT_MODE),
+        Settings.Global.getUriFor(PRIVATE_DNS_SPECIFIER),
     };
 
     private final Handler mHandler;

tests/robotests/src/com/android/settings/network/PrivateDnsModeDialogPreferenceTest.java

@@ -19,6 +19,7 @@ package com.android.settings.network;
 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;
+import static android.provider.Settings.Global.PRIVATE_DNS_MODE;
 import static com.google.common.truth.Truth.assertThat;
 import static org.mockito.Mockito.anyInt;
 import static org.mockito.Mockito.doReturn;
@@ -158,24 +159,21 @@ public class PrivateDnsModeDialogPreferenceTest {
     public void testOnClick_positiveButtonClicked_saveData() {
         // Set the default settings to OFF
         final ContentResolver contentResolver = mContext.getContentResolver();
-        Settings.Global.putString(contentResolver, Settings.Global.PRIVATE_DNS_MODE,
+        Settings.Global.putString(contentResolver, PRIVATE_DNS_MODE, PRIVATE_DNS_MODE_OFF);
-                ConnectivityManager.PRIVATE_DNS_MODE_OFF);
 
         mPreference.mMode = ConnectivityManager.PRIVATE_DNS_MODE_OPPORTUNISTIC;
         mPreference.onClick(null, DialogInterface.BUTTON_POSITIVE);
 
         // Change to OPPORTUNISTIC
-        assertThat(Settings.Global.getString(contentResolver,
+        assertThat(Settings.Global.getString(contentResolver, PRIVATE_DNS_MODE)).isEqualTo(
-                Settings.Global.PRIVATE_DNS_MODE)).isEqualTo(
+                PRIVATE_DNS_MODE_OPPORTUNISTIC);
-                ConnectivityManager.PRIVATE_DNS_MODE_OPPORTUNISTIC);
     }
 
     @Test
     public void testOnClick_negativeButtonClicked_doNothing() {
         // Set the default settings to OFF
         final ContentResolver contentResolver = mContext.getContentResolver();
-        Settings.Global.putString(contentResolver, Settings.Global.PRIVATE_DNS_MODE,
+        Settings.Global.putString(contentResolver, PRIVATE_DNS_MODE, PRIVATE_DNS_MODE_OFF);
-                ConnectivityManager.PRIVATE_DNS_MODE_OFF);
 
         mPreference.mMode = ConnectivityManager.PRIVATE_DNS_MODE_OPPORTUNISTIC;
         mPreference.onClick(null, DialogInterface.BUTTON_NEGATIVE);

tests/robotests/src/com/android/settings/network/PrivateDnsPreferenceControllerTest.java

@@ -21,6 +21,7 @@ import static android.arch.lifecycle.Lifecycle.Event.ON_STOP;
 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;
+import static android.provider.Settings.Global.PRIVATE_DNS_DEFAULT_MODE;
 import static android.provider.Settings.Global.PRIVATE_DNS_MODE;
 import static android.provider.Settings.Global.PRIVATE_DNS_SPECIFIER;
 import static com.google.common.truth.Truth.assertThat;
@@ -220,6 +221,34 @@ public class PrivateDnsPreferenceControllerTest {
                 getResourceString(R.string.private_dns_mode_provider_failure));
     }
 
+    @Test
+    public void getSummary_PrivateDnsDefaultMode() {
+        // Default mode is opportunistic, unless overridden by a Settings push.
+        setPrivateDnsMode("");
+        setPrivateDnsProviderHostname("");
+        mController.updateState(mPreference);
+        verify(mController, atLeastOnce()).getSummary();
+        verify(mPreference).setSummary(getResourceString(R.string.private_dns_mode_opportunistic));
+
+        reset(mController);
+        reset(mPreference);
+        // Pretend an emergency gservices setting has disabled default-opportunistic.
+        Settings.Global.putString(mContentResolver, PRIVATE_DNS_DEFAULT_MODE, PRIVATE_DNS_MODE_OFF);
+        mController.updateState(mPreference);
+        verify(mController, atLeastOnce()).getSummary();
+        verify(mPreference).setSummary(getResourceString(R.string.private_dns_mode_off));
+
+        reset(mController);
+        reset(mPreference);
+        // The user interacting with the Private DNS menu, explicitly choosing
+        // opportunistic mode, will be able to use despite the change to the
+        // default setting above.
+        setPrivateDnsMode(PRIVATE_DNS_MODE_OPPORTUNISTIC);
+        mController.updateState(mPreference);
+        verify(mController, atLeastOnce()).getSummary();
+        verify(mPreference).setSummary(getResourceString(R.string.private_dns_mode_opportunistic));
+    }
+
     private void setPrivateDnsMode(String mode) {
         Settings.Global.putString(mContentResolver, PRIVATE_DNS_MODE, mode);
     }