Remove unused packaged app window controls code.

extensions/renderer/app_window_custom_bindings.h

Index: extensions/renderer/app_window_custom_bindings.h
diff --git a/extensions/renderer/app_window_custom_bindings.h b/extensions/renderer/app_window_custom_bindings.h
index b8054c07a60ebd096dbc5754cec89fbb1e99b889..cd15629cd4d2db435e48d40153cff5782a8f2549 100644
--- a/extensions/renderer/app_window_custom_bindings.h
+++ b/extensions/renderer/app_window_custom_bindings.h
@@ -18,11 +18,6 @@ class AppWindowCustomBindings : public ObjectBackedNativeHandler {
  private:
   void GetFrame(const v8::FunctionCallbackInfo<v8::Value>& args);
 
-  // Return string containing the HTML <template> for the <window-controls>
-  // custom element.
-  void GetWindowControlsHtmlTemplate(
-      const v8::FunctionCallbackInfo<v8::Value>& args);
-
   DISALLOW_COPY_AND_ASSIGN(AppWindowCustomBindings);
 };