Update AutoImport to import nothing by default (in absence of policy and master_prefs).

chrome/installer/util/master_preferences.cc

Index: chrome/installer/util/master_preferences.cc
diff --git a/chrome/installer/util/master_preferences.cc b/chrome/installer/util/master_preferences.cc
index fa014177d8bafcabf091067ad029f6a4e9e87633..223aa320065ed7e21a75fa02eccc24cefa8d1d8f 100644
--- a/chrome/installer/util/master_preferences.cc
+++ b/chrome/installer/util/master_preferences.cc
@@ -226,6 +226,29 @@ void MasterPreferences::EnforceLegacyPreferences() {
         installer::master_preferences::kDoNotCreateQuickLaunchShortcut, true);
   }
 
+  // Deprecated boolean import master preferences now mapped to their duplicates
+  // in prefs::.
+  static constexpr char kDistroImportHistoryPref[] = "import_history";
+  static constexpr char kDistroImportHomePagePref[] = "import_home_page";
+  static constexpr char kDistroImportSearchPref[] = "import_search_engine";
+  static constexpr char kDistroImportBookmarksPref[] = "import_bookmarks";
+
+  static constexpr struct {
+    const char* old_distro_pref_path;
+    const char* modern_pref_path;
+  } kLegacyDistroImportPrefMappings[] = {
+      {kDistroImportBookmarksPref, prefs::kImportBookmarks},
+      {kDistroImportHistoryPref, prefs::kImportHistory},
+      {kDistroImportHomePagePref, prefs::kImportHomepage},
+      {kDistroImportSearchPref, prefs::kImportSearchEngine},
+  };
+
+  for (const auto& mapping : kLegacyDistroImportPrefMappings) {
+    bool value = false;
+    if (GetBool(mapping.old_distro_pref_path, &value))
+      master_dictionary_->SetBoolean(mapping.modern_pref_path, value);
+  }
+
 #if BUILDFLAG(ENABLE_RLZ)
   // Map the RLZ ping delay shipped in the distribution dictionary into real
   // prefs.