Avoid touching fonts in ResourceBundle while reloading locale

chrome/browser/chromeos/base/locale_util.cc

 // Copyright 2013 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/base/locale_util.h"
 
 #include <utility>
 #include <vector>
 
 #include "base/task_scheduler/post_task.h"
@@ skipping 33 matching lines @@
 // Runs on SequencedWorkerPool thread under PostTaskAndReply().
 // So data is owned by "Reply" part of PostTaskAndReply() process.
 void SwitchLanguageDoReloadLocale(SwitchLanguageData* data) {
   DCHECK(!content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
 
   data->result.loaded_locale =
       ResourceBundle::GetSharedInstance().ReloadLocaleResources(
           data->result.requested_locale);
 
   data->result.success = !data->result.loaded_locale.empty();
-
-  ResourceBundle::GetSharedInstance().ReloadFonts();
 }
 
 // Callback after SwitchLanguageDoReloadLocale() back in UI thread.
 void FinishSwitchLanguage(std::unique_ptr<SwitchLanguageData> data) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   if (data->result.success) {
     g_browser_process->SetApplicationLocale(data->result.loaded_locale);
 
     if (data->enable_locale_keyboard_layouts) {
       input_method::InputMethodManager* manager =
@@ skipping 20 matching lines @@
             data->result.loaded_locale,
             input_method::kKeyboardLayoutsOnly,
             &input_methods);
         for (std::vector<std::string>::const_iterator it =
                 input_methods.begin(); it != input_methods.end(); ++it) {
           ime_state->EnableInputMethod(*it);
         }
       }
     }
   }
+
+  // The font clean up of ResourceBundle should be done on UI thread, since the
+  // cached fonts are thread unsafe.
+  ResourceBundle::GetSharedInstance().ReloadFonts();

[sky, 2017/02/21 17:51:06]

Could you make ReloadFonts DCHECK it's on the main thread?

   gfx::PlatformFontLinux::ReloadDefaultFont();
   if (!data->callback.is_null())
     data->callback.Run(data->result);
 }
 
 }  // namespace
 
 namespace locale_util {
 
 LanguageSwitchResult::LanguageSwitchResult(const std::string& requested_locale,
@@ skipping 17 matching lines @@
       base::Bind(&SwitchLanguageDoReloadLocale, base::Unretained(data.get())));
   base::PostTaskWithTraitsAndReply(
       FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
                      base::TaskPriority::BACKGROUND),
       reloader,
       base::Bind(&FinishSwitchLanguage, base::Passed(std::move(data))));
 }
 
 }  // namespace locale_util
 }  // namespace chromeos