Do not sync prefs::kLanguagePreloadEngines and prefs::kLanguagePreferredLanguages.

chrome/browser/chromeos/preferences.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chromeos/preferences.h"
 
 #include "base/i18n/time_formatting.h"
 #include "base/metrics/histogram.h"
 #include "base/string_split.h"
 #include "base/string_util.h"
@@ skipping 39 matching lines @@
     prefs->RegisterBooleanPref(prefs::kAccessibilityEnabled,
                                false,
                                PrefService::UNSYNCABLE_PREF);
   }
   prefs->RegisterIntegerPref(prefs::kTouchpadSensitivity,
                              3,
                              PrefService::UNSYNCABLE_PREF);
   prefs->RegisterBooleanPref(prefs::kUse24HourClock,
                              base::GetHourClockType() == base::k24HourClock,
                              PrefService::SYNCABLE_PREF);
+  // We don't sync prefs::kLanguageCurrentInputMethod and PreviousInputMethod
+  // because they're just used to track the logout state of the device.
   prefs->RegisterStringPref(prefs::kLanguageCurrentInputMethod,
                             "",
                             PrefService::UNSYNCABLE_PREF);
   prefs->RegisterStringPref(prefs::kLanguagePreviousInputMethod,
                             "",
                             PrefService::UNSYNCABLE_PREF);
+  // We don't sync input method hotkeys since they're not configurable.
   prefs->RegisterStringPref(prefs::kLanguageHotkeyNextEngineInMenu,
                             language_prefs::kHotkeyNextEngineInMenu,
                             PrefService::UNSYNCABLE_PREF);
   prefs->RegisterStringPref(prefs::kLanguageHotkeyPreviousEngine,
                             language_prefs::kHotkeyPreviousEngine,
                             PrefService::UNSYNCABLE_PREF);
+  // We don't sync the list of input methods and preferred languages since a
+  // user might use two or more devices with different hardware keyboards.
+  // crosbug.com/15181
   prefs->RegisterStringPref(prefs::kLanguagePreferredLanguages,
                             kFallbackInputMethodLocale,
-                            PrefService::SYNCABLE_PREF);
+                            PrefService::UNSYNCABLE_PREF);
   prefs->RegisterStringPref(prefs::kLanguagePreloadEngines,
                             input_method::GetHardwareInputMethodId(),
-                            PrefService::SYNCABLE_PREF);
+                            PrefService::UNSYNCABLE_PREF);
   for (size_t i = 0; i < language_prefs::kNumChewingBooleanPrefs; ++i) {
     prefs->RegisterBooleanPref(
         language_prefs::kChewingBooleanPrefs[i].pref_name,
         language_prefs::kChewingBooleanPrefs[i].default_pref_value,
         PrefService::UNSYNCABLE_PREF);
   }
   for (size_t i = 0; i < language_prefs::kNumChewingMultipleChoicePrefs; ++i) {
     prefs->RegisterStringPref(
         language_prefs::kChewingMultipleChoicePrefs[i].pref_name,
         language_prefs::kChewingMultipleChoicePrefs[i].default_pref_value,
@@ skipping 54 matching lines @@
   }
   prefs->RegisterIntegerPref(prefs::kLanguageXkbRemapSearchKeyTo,
                              input_method::kSearchKey,
                              PrefService::SYNCABLE_PREF);
   prefs->RegisterIntegerPref(prefs::kLanguageXkbRemapControlKeyTo,
                              input_method::kLeftControlKey,
                              PrefService::SYNCABLE_PREF);
   prefs->RegisterIntegerPref(prefs::kLanguageXkbRemapAltKeyTo,
                              input_method::kLeftAltKey,
                              PrefService::SYNCABLE_PREF);
+  // We don't sync the following keyboard prefs since they are not user-
+  // configurable.
   prefs->RegisterBooleanPref(prefs::kLanguageXkbAutoRepeatEnabled,
                              true,
                              PrefService::UNSYNCABLE_PREF);
   prefs->RegisterIntegerPref(prefs::kLanguageXkbAutoRepeatDelay,
                              language_prefs::kXkbAutoRepeatDelayInMs,
                              PrefService::UNSYNCABLE_PREF);
   prefs->RegisterIntegerPref(prefs::kLanguageXkbAutoRepeatInterval,
                              language_prefs::kXkbAutoRepeatIntervalInMs,
                              PrefService::UNSYNCABLE_PREF);
 
@@ skipping 365 matching lines @@
   input_method::AutoRepeatRate rate;
   rate.initial_delay_in_ms = language_xkb_auto_repeat_delay_pref_.GetValue();
   rate.repeat_interval_in_ms =
       language_xkb_auto_repeat_interval_pref_.GetValue();
   DCHECK(rate.initial_delay_in_ms > 0);
   DCHECK(rate.repeat_interval_in_ms > 0);
   input_method::SetAutoRepeatRate(rate);
 }
 
 }  // namespace chromeos