Add synchronization around access when using ReloadLocaleResources

ui/base/resource/resource_bundle.cc

Index: ui/base/resource/resource_bundle.cc
diff --git a/ui/base/resource/resource_bundle.cc b/ui/base/resource/resource_bundle.cc
index 417fd2bb11b35ac47b340ff38f7dc02904f2f6b6..0d64241ed67284513a8285dd6fee517e4e54f5b8 100644
--- a/ui/base/resource/resource_bundle.cc
+++ b/ui/base/resource/resource_bundle.cc
@@ -163,6 +163,7 @@ std::string ResourceBundle::LoadLocaleResources(
 
   if (locale_file_path.empty()) {
     // It's possible that there is no locale.pak.
+    DLOG(WARNING) << "locale_file_path.empty()";
     return std::string();
   }
 
@@ -303,6 +304,8 @@ base::StringPiece ResourceBundle::GetRawDataResource(
       delegate_->GetRawDataResource(resource_id, scale_factor, &data))
     return data;
 
+  // TODO(tony): Firm up locking for or constraints of calling
+  // ReloadLocaleResources() and how to CHECK for misuse.
   DCHECK(locale_resources_data_.get());
   if (locale_resources_data_->GetStringPiece(resource_id, &data))
     return data;