Cleanup: Remove unused ui::ResourceBundle::ImageRTL

ui/base/resource/resource_bundle_auralinux.cc

Index: ui/base/resource/resource_bundle_auralinux.cc
diff --git a/ui/base/resource/resource_bundle_auralinux.cc b/ui/base/resource/resource_bundle_auralinux.cc
index 7365b1df3d14ed4436b939e397e19e10170f81c1..8989a9e49c49fa47775ebae79ce5a97f504c7bc4 100644
--- a/ui/base/resource/resource_bundle_auralinux.cc
+++ b/ui/base/resource/resource_bundle_auralinux.cc
@@ -20,9 +20,7 @@ void ResourceBundle::LoadCommonResources() {
   LoadChromeResources();
 }
 
-gfx::Image& ResourceBundle::GetNativeImageNamed(int resource_id, ImageRTL rtl) {
-  // Flipped image is not used on ChromeOS.
-  DCHECK_EQ(rtl, RTL_DISABLED);
+gfx::Image& ResourceBundle::GetNativeImageNamed(int resource_id) {
   return GetImageNamed(resource_id);
 }