Bug 40022: Migrate Tor security level from Fennec

components/support/migration/src/main/java/mozilla/components/support/migration/FennecMigrator.kt

@@ -991,7 +991,7 @@ class FennecMigrator private constructor(
 
         return try {
             logger.debug("Migrating gecko files...")
-            val result = GeckoMigration.migrate(profile.path, migrationVersion)
+            val result = GeckoMigration.migrate(profile.path, migrationVersion, context)
             logger.debug("Migrated gecko files.")
 
             if (result is Result.Failure<GeckoMigrationResult>) {

components/support/migration/src/main/java/mozilla/components/support/migration/GeckoMigration.kt

@@ -4,6 +4,7 @@
 
 package mozilla.components.support.migration
 
+import android.content.Context
 import android.util.AtomicFile
 import androidx.annotation.VisibleForTesting
 import mozilla.components.support.ktx.util.writeString
@@ -95,7 +96,8 @@ internal object GeckoMigration {
      */
     fun migrate(
         profilePath: String,
-        migrationVersion: Int
+        migrationVersion: Int,
+        context: Context
     ): Result<GeckoMigrationResult> {
         // GeckoView will happily pick up the profile from Fennec and reuse all data in it. So this
         // migration is mostly focused on removing all prefs that we do not want to reuse.
@@ -118,6 +120,23 @@ internal object GeckoMigration {
             }.toList()
         }
 
+        val secLevel = prefsjs.useLines {
+            // The prefs are auto-generated, so we can expect the offset to be always the same
+            it.find { line -> line.startsWith("$USER_PREF(\"extensions.torbutton.security_slider\"") }
+                    ?.substring(50, 51)?.toIntOrNull()
+        }
+        if (secLevel != null && secLevel > 0 && secLevel < 4) {
+            val prefVal = when (secLevel) {
+                1 -> "pref_key_tor_security_level_safest_option"
+                else -> "pref_key_tor_security_level_safer_option"
+            }
+            val fenixAppPrefs = context.getSharedPreferences(FennecSettingsMigration.FENIX_SHARED_PREFS_NAME, Context.MODE_PRIVATE)
+            fenixAppPrefs.edit()
+                    .putBoolean("pref_key_tor_security_level_standard_option", false)
+                    .putBoolean(prefVal, true)
+                    .apply()
+        }
+
         return if (transformed.isEmpty()) {
             removePrefsFile(prefsjs)
         } else {