Remove some unused theming code for GTK.

chrome/browser/themes/theme_service_aurax11.cc

Index: chrome/browser/themes/theme_service_aurax11.cc
diff --git a/chrome/browser/themes/theme_service_aurax11.cc b/chrome/browser/themes/theme_service_aurax11.cc
index 71a573ab303036f13f63031db536f328bff3cb82..722443176325e101dbad9fbaa84bd2d1bfe0f0d7 100644
--- a/chrome/browser/themes/theme_service_aurax11.cc
+++ b/chrome/browser/themes/theme_service_aurax11.cc
@@ -65,11 +65,11 @@ bool SystemThemeX11::GetColor(int id, SkColor* color) const {
 }
 
 gfx::Image SystemThemeX11::GetImageNamed(int id) {
-  return linux_ui_ ? linux_ui_->GetThemeImageNamed(id) : gfx::Image();
+  return gfx::Image();
 }
 
 bool SystemThemeX11::HasCustomImage(int id) const {
-  return linux_ui_ && linux_ui_->HasCustomImage(id);
+  return false;
 }
 
 SystemThemeX11::~SystemThemeX11() {}