Rejigger ThemeService: move exposure of ThemeProvider interface to a

ui/base/default_theme_provider.cc

Index: ui/base/default_theme_provider.cc
diff --git a/ui/base/default_theme_provider.cc b/ui/base/default_theme_provider.cc
index 210ff1899b979410e5c9be653614a41e71e2d4fc..899661c5bb5fb3f4d036e03cc5955d4845b1c1db 100644
--- a/ui/base/default_theme_provider.cc
+++ b/ui/base/default_theme_provider.cc
@@ -13,10 +13,6 @@ DefaultThemeProvider::DefaultThemeProvider() {}
 
 DefaultThemeProvider::~DefaultThemeProvider() {}
 
-bool DefaultThemeProvider::UsingSystemTheme() const {
-  return true;
-}
-
 gfx::ImageSkia* DefaultThemeProvider::GetImageSkiaNamed(int id) const {
   return ResourceBundle::GetSharedInstance().GetImageSkiaNamed(id);
 }