Cleanup: Remove unused ui::ResourceBundle::ImageRTL

ui/base/resource/resource_bundle_mac.mm

Index: ui/base/resource/resource_bundle_mac.mm
diff --git a/ui/base/resource/resource_bundle_mac.mm b/ui/base/resource/resource_bundle_mac.mm
index 74d8261560623953aa66ec7550346d484bd200d3..93af893054ce0c32a05be81a3f3ea53515fc70ac 100644
--- a/ui/base/resource/resource_bundle_mac.mm
+++ b/ui/base/resource/resource_bundle_mac.mm
@@ -104,10 +104,7 @@ base::FilePath ResourceBundle::GetLocaleFilePath(const std::string& app_locale,
   return locale_file_path;
 }
 
-gfx::Image& ResourceBundle::GetNativeImageNamed(int resource_id, ImageRTL rtl) {
-  // Flipped images are not used on Mac.
-  DCHECK_EQ(rtl, RTL_DISABLED);
-
+gfx::Image& ResourceBundle::GetNativeImageNamed(int resource_id) {
   // Check to see if the image is already in the cache.
   {
     base::AutoLock lock(*images_and_fonts_lock_);
@@ -124,7 +121,7 @@ gfx::Image& ResourceBundle::GetNativeImageNamed(int resource_id, ImageRTL rtl) {
 
   gfx::Image image;
   if (delegate_)
-    image = delegate_->GetNativeImageNamed(resource_id, rtl);
+    image = delegate_->GetNativeImageNamed(resource_id);
 
   bool found_in_a_material_design_pack = false;