Only add the UI language to Fluent Language list

Bug: 958348
Change-Id: I3245764685899068e126025a1f164018cac9965d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1602597Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: anthonyvd <anthonyvd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#658246}

components/language/core/browser/language_prefs.cc

@@ -99,11 +99,24 @@ base::Value LanguagePrefs::GetDefaultFluentLanguages() {
                          base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL)) {
     language::ToTranslateLanguageSynonym(&language);
     languages.insert(std::move(language));
+
+    // crbug.com/958348: The default value for Accept-Language *should* be the
+    // same as the one for Fluent Languages. However, Accept-Language contains
+    // English (and more) in addition to the local language in most locales due
+    // to historical reasons. Exiting early from this loop is a temporary fix
+    // that allows Fluent Languages to be at least populated with the UI
+    // language while still allowing Translate to trigger on other languages,
+    // most importantly English.
+    // Once the change to remove English from Accept-Language defaults lands,
+    // this break should be removed to enable the Fluent Language List and the
+    // Accept-Language list to be initialized to the same values.
+    break;
   }
 #endif
   base::Value language_values(base::Value::Type::LIST);
   for (const std::string& language : languages)
     language_values.GetList().emplace_back(language);
+
   return language_values;
 }