For //chrome/updater metainstaller, use preferred UI language from MUI

For the ChromiumUpdater, instead of reading the language tag, use
GetUserPreferredUILanguageList to get the preferred UI language from
MUI.

Bug: 1281969
Change-Id: Ib5f6141a95976ada0d9c6f5964636931a7c3ff2b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3594230
Reviewed-by: Joshua Pawlicki <waffles@chromium.org>
Reviewed-by: Sorin Jianu <sorin@chromium.org>
Commit-Queue: Dong Sung Chang <donchan@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#994400}

chrome/updater/win/ui/l10n_util.cc

@@ -14,6 +14,7 @@
 #include "base/strings/sys_string_conversions.h"
 #include "base/win/atl.h"
 #include "base/win/embedded_i18n/language_selector.h"
+#include "base/win/i18n.h"
 #include "chrome/updater/tag.h"
 #include "chrome/updater/util.h"
 #include "chrome/updater/win/ui/resources/updater_installer_strings.h"
@@ -28,22 +29,19 @@ constexpr base::win::i18n::LanguageSelector::LangToOffset
 #undef HANDLE_LANGUAGE
 };
 
-std::wstring GetPreferredLanguageFromGoogleUpdate() {
-  const TagParsingResult tag_parsing_result = GetTagArgs();
-  if (tag_parsing_result.error != tagging::ErrorCode::kSuccess) {
-    VLOG(0) << "Couldn't parse the tag!";
-    return {};
+std::wstring GetPreferredLanguage() {
+  std::vector<std::wstring> languages;
+  if (!base::win::i18n::GetUserPreferredUILanguageList(&languages) ||
+      languages.size() == 0) {
+    return L"en-us";
   }
-  const tagging::TagArgs tag_args =
-      tag_parsing_result.tag_args.value_or(tagging::TagArgs());
 
-  return tag_args.language.empty() ? L"en-us"
-                                   : base::SysUTF8ToWide(tag_args.language);
+  return languages[0];
 }
 
 const base::win::i18n::LanguageSelector& GetLanguageSelector() {
   static base::NoDestructor<base::win::i18n::LanguageSelector> instance(
-      GetPreferredLanguageFromGoogleUpdate(), kLanguageOffsetPairs);
+      GetPreferredLanguage(), kLanguageOffsetPairs);
   return *instance;
 }
 

docs/updater/design_doc.md

@@ -544,4 +544,7 @@ strings. `GetLocalizedString()` uses the base id plus the offset based on the
 language to look through the binary's string table to get the correct, localized
 string. The formatted strings utilize GetLocalizedString() to get the string and
 then uses `base::ReplaceStringPlaceholders()` to remove the `$i` placeholders
-within the string.
+within the string. With regards to picking the correct language to utilize for
+the localized string, `base::win::i18n::GetUserPreferredUILanguageList()` is
+used to get the preferred UI languages from MUI. If there are multiple languages
+in the list, the first language in the list is picked.

docs/updater/functional_spec.md

@@ -21,8 +21,9 @@ The metainstaller parses its tag and re-launches itself at high integrity if
 installing an application with `needsadmin=true` or `needsadmin=prefers`.
 
 ### Localization
-Metainstaller localization presents the metainstaller UI in the language of
-choice on download. Every string shown in the UI is translated. 
+Metainstaller localization presents the metainstaller UI with the user's
+preferred language on the current system. Every string shown in the UI is
+translated. 
 
 ## Standalone Installer
 TODO(crbug.com/1035895): Document the standalone installer.