For #20919 quite the app when turning on/off experiments

app/src/main/java/org/mozilla/fenix/settings/DataChoicesFragment.kt

@@ -5,6 +5,9 @@
 package org.mozilla.fenix.settings
 
 import android.os.Bundle
+import android.os.Handler
+import android.os.Looper
+import android.widget.Toast
 import androidx.preference.PreferenceFragmentCompat
 import androidx.preference.SwitchPreference
 import org.mozilla.fenix.R
@@ -13,6 +16,7 @@ import org.mozilla.fenix.ext.components
 import org.mozilla.fenix.ext.getPreferenceKey
 import org.mozilla.fenix.ext.settings
 import org.mozilla.fenix.ext.showToolbar
+import kotlin.system.exitProcess
 
 /**
  * Lets the user toggle telemetry on/off.
@@ -43,6 +47,17 @@ class DataChoicesFragment : PreferenceFragmentCompat() {
             } else if (key == getPreferenceKey(R.string.pref_key_experimentation)) {
                 val enabled = context.settings().isExperimentationEnabled
                 context.components.analytics.experiments.globalUserParticipation = enabled
+                Toast.makeText(
+                    context,
+                    getQuittingAppString(),
+                    Toast.LENGTH_LONG
+                ).show()
+                Handler(Looper.getMainLooper()).postDelayed(
+                    {
+                        exitProcess(0)
+                    },
+                    OVERRIDE_EXIT_DELAY
+                )
             }
         }
     }
@@ -74,4 +89,22 @@ class DataChoicesFragment : PreferenceFragmentCompat() {
             onPreferenceChangeListener = SharedPreferenceUpdater()
         }
     }
+
+    @Suppress("TooGenericExceptionCaught")
+    private fun getQuittingAppString(): String {
+        // Fix for #20919. As we are not able to get new strings on Beta and Release,
+        // We are using a string that it's already translated and taking some parts of it.
+        // To be specific "Firefox Account/Sync server modified. Quitting the application to apply changes…"
+        // We are interested on the phrase after the dot, that is generic and we can use for this case.
+        val rawString = getString(R.string.toast_override_fxa_sync_server_done)
+        return try {
+            rawString.split(".")[1]
+        } catch (e: ArrayIndexOutOfBoundsException) {
+            rawString
+        }
+    }
+
+    companion object {
+        private const val OVERRIDE_EXIT_DELAY = 3000L
+    }
 }