Bug 1821187 - Add infrastructure for file migrators in the new Migration Wizard. r=fluent-reviewers,kpatenio,flod

This also includes our first file migrator, which imports passwords from CSV/TSV files.

Differential Revision: https://phabricator.services.mozilla.com/D173033

browser/components/migration/MigrationUtils.sys.mjs

@@ -17,6 +17,7 @@ ChromeUtils.defineESModuleGetters(lazy, {
 });
 
 var gMigrators = null;
+var gFileMigrators = null;
 var gProfileStartup = null;
 var gL10n = null;
 var gPreviousDefaultBrowserKey = "";
@@ -107,6 +108,12 @@ const MIGRATOR_MODULES = Object.freeze({
   },
 });
 
+const FILE_MIGRATOR_MODULES = Object.freeze({
+  PasswordFileMigrator: {
+    moduleURI: "resource:///modules/FileMigrators.sys.mjs",
+  },
+});
+
 /**
  * The singleton MigrationUtils service. This service is the primary mechanism
  * by which migrations from other browsers to this browser occur. The singleton
@@ -301,6 +308,26 @@ class MigrationUtils {
     return gMigrators;
   }
 
+  get #fileMigrators() {
+    if (!gFileMigrators) {
+      gFileMigrators = new Map();
+      for (let [symbol, { moduleURI }] of Object.entries(
+        FILE_MIGRATOR_MODULES
+      )) {
+        let { [symbol]: migratorClass } = ChromeUtils.importESModule(moduleURI);
+        if (gFileMigrators.has(migratorClass.key)) {
+          console.error(
+            "A pre-existing file migrator exists with key " +
+              `${migratorClass.key}. Not registering.`
+          );
+          continue;
+        }
+        gFileMigrators.set(migratorClass.key, new migratorClass());
+      }
+    }
+    return gFileMigrators;
+  }
+
   forceExitSpinResolve() {
     gForceExitSpinResolve = true;
   }
@@ -367,6 +394,15 @@ class MigrationUtils {
     }
   }
 
+  getFileMigrator(aKey) {
+    let migrator = this.#fileMigrators.get(aKey);
+    if (!migrator) {
+      console.error(`Could not find a file migrator class for key ${aKey}`);
+      return null;
+    }
+    return migrator;
+  }
+
   /**
    * Returns true if a migrator is registered with key aKey. No check is made
    * to determine if a profile exists that the migrator can migrate from.
@@ -958,6 +994,10 @@ class MigrationUtils {
     return [...this.#migrators.keys()];
   }
 
+  get availableFileMigrators() {
+    return [...this.#fileMigrators.values()];
+  }
+
   /**
    * Enum for the entrypoint that is being used to start migration.
    * Callers can use the MIGRATION_ENTRYPOINTS getter to use these.