Make AppWindowCreateFunction UIThreadExtensionFunction.

extensions/browser/api/app_window/app_window_api.h

Index: extensions/browser/api/app_window/app_window_api.h
diff --git a/extensions/browser/api/app_window/app_window_api.h b/extensions/browser/api/app_window/app_window_api.h
index f10ec989b497646a806b92ec103011b47c19ae61..27a8ef0fd12e8541b6dd584edb039d46cbecc170 100644
--- a/extensions/browser/api/app_window/app_window_api.h
+++ b/extensions/browser/api/app_window/app_window_api.h
@@ -16,14 +16,14 @@ struct CreateWindowOptions;
 }
 }
 
-class AppWindowCreateFunction : public AsyncExtensionFunction {
+class AppWindowCreateFunction : public UIThreadExtensionFunction {
  public:
   AppWindowCreateFunction();
   DECLARE_EXTENSION_FUNCTION("app.window.create", APP_WINDOW_CREATE)
 
  protected:
   ~AppWindowCreateFunction() override {}
-  bool RunAsync() override;
+  ResponseAction Run() override;
 
  private:
   bool GetBoundsSpec(
@@ -34,7 +34,8 @@ class AppWindowCreateFunction : public AsyncExtensionFunction {
   AppWindow::Frame GetFrameFromString(const std::string& frame_string);
   bool GetFrameOptions(
       const extensions::api::app_window::CreateWindowOptions& options,
-      AppWindow::CreateParams* create_params);
+      AppWindow::CreateParams* create_params,
+      std::string* error);
   void UpdateFrameOptionsForChannel(AppWindow::CreateParams* create_params);
 };