chore: remove unused arg from BaseWindow::GetBackgroundColor() (#44906)

chore: remove unused gin_helper::Arguments* arg from BaseWindow::GetBackgroundColor()

looks like this was added in db79734b but never used

shell/browser/api/electron_api_base_window.cc

@@ -669,7 +669,7 @@ void BaseWindow::SetBackgroundColor(const std::string& color_name) {
   window_->SetBackgroundColor(color);
 }
 
-std::string BaseWindow::GetBackgroundColor(gin_helper::Arguments* args) const {
+std::string BaseWindow::GetBackgroundColor() const {
   return ToRGBHex(window_->GetBackgroundColor());
 }
 

shell/browser/api/electron_api_base_window.h

@@ -164,7 +164,7 @@ class BaseWindow : public gin_helper::TrackableObject<BaseWindow>,
   bool IsKiosk() const;
   bool IsTabletMode() const;
   virtual void SetBackgroundColor(const std::string& color_name);
-  std::string GetBackgroundColor(gin_helper::Arguments* args) const;
+  std::string GetBackgroundColor() const;
   void InvalidateShadow();
   void SetHasShadow(bool has_shadow);
   bool HasShadow() const;