Enables the user to select multiple languages for spellchecking (UI)

chrome/browser/spellchecker/spellcheck_factory.cc

Index: chrome/browser/spellchecker/spellcheck_factory.cc
diff --git a/chrome/browser/spellchecker/spellcheck_factory.cc b/chrome/browser/spellchecker/spellcheck_factory.cc
index edbed4055410f4b5c9027f3023dea245aa2fd68d..ed530e7ff9375d007d08ac6e930a59d45b3f1474 100644
--- a/chrome/browser/spellchecker/spellcheck_factory.cc
+++ b/chrome/browser/spellchecker/spellcheck_factory.cc
@@ -4,10 +4,13 @@
 
 #include "chrome/browser/spellchecker/spellcheck_factory.h"
 
+#include "base/command_line.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/profiles/incognito_helpers.h"
 #include "chrome/browser/spellchecker/spellcheck_service.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/pref_names.h"
+#include "chrome/common/spellcheck_common.h"
 #include "chrome/grit/locale_settings.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "components/pref_registry/pref_registry_syncable.h"
@@ -69,9 +72,21 @@ KeyedService* SpellcheckServiceFactory::BuildServiceInstanceFor(
 void SpellcheckServiceFactory::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* user_prefs) {
   // TODO(estade): IDS_SPELLCHECK_DICTIONARY should be an ASCII string.
-  user_prefs->RegisterStringPref(
-      prefs::kSpellCheckDictionary,
-      l10n_util::GetStringUTF8(IDS_SPELLCHECK_DICTIONARY));
+
+  // TODO(juliusa): Implement preference migration between multilingual
+  // spellchecking and single-language spellchecking.
+  if (chrome::spellcheck_common::MultilingualSpellcheckIsEnabled()) {
+    user_prefs->RegisterStringPref(
+        prefs::kSpellCheckDictionaries,
+        l10n_util::GetStringUTF8(IDS_SPELLCHECK_DICTIONARY),
+        user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
+  } else {
+    user_prefs->RegisterStringPref(
+        prefs::kSpellCheckDictionary,
+        l10n_util::GetStringUTF8(IDS_SPELLCHECK_DICTIONARY),
+        user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
+  }
+
   user_prefs->RegisterBooleanPref(prefs::kSpellCheckUseSpellingService, false);
   user_prefs->RegisterBooleanPref(
       prefs::kEnableContinuousSpellcheck,