fix: transparency on child windows being lost (#31003)

* fix: transparency on child windows being lost

* fix crash

* fix a different crash

* fix more crash

shell/browser/api/electron_api_browser_window.cc

@@ -362,7 +362,11 @@ void BrowserWindow::Blur() {
 
 void BrowserWindow::SetBackgroundColor(const std::string& color_name) {
   BaseWindow::SetBackgroundColor(color_name);
-  web_contents()->SetPageBaseBackgroundColor(ParseHexColor(color_name));
+  SkColor color = ParseHexColor(color_name);
+  web_contents()->SetPageBaseBackgroundColor(color);
+  auto* rwhv = web_contents()->GetRenderWidgetHostView();
+  if (rwhv)
+    rwhv->SetBackgroundColor(color);
   // Also update the web preferences object otherwise the view will be reset on
   // the next load URL call
   if (api_web_contents_) {

shell/browser/api/electron_api_web_contents.cc

@@ -1373,8 +1373,9 @@ void WebContents::HandleNewRenderFrame(
   // Set the background color of RenderWidgetHostView.
   auto* web_preferences = WebContentsPreferences::From(web_contents());
   if (web_preferences) {
-    web_contents()->SetPageBaseBackgroundColor(
-        web_preferences->GetBackgroundColor());
+    absl::optional<SkColor> color = web_preferences->GetBackgroundColor();
+    web_contents()->SetPageBaseBackgroundColor(color);
+    rwhv->SetBackgroundColor(color.value_or(SK_ColorWHITE));
   }
 
   if (!background_throttling_)
@@ -3866,6 +3867,12 @@ gin::Handle<WebContents> WebContents::CreateFromWebPreferences(
     if (gin::ConvertFromV8(isolate, web_preferences.GetHandle(),
                            &web_preferences_dict)) {
       existing_preferences->SetFromDictionary(web_preferences_dict);
+      absl::optional<SkColor> color =
+          existing_preferences->GetBackgroundColor();
+      web_contents->web_contents()->SetPageBaseBackgroundColor(color);
+      auto* rwhv = web_contents->web_contents()->GetRenderWidgetHostView();
+      if (rwhv)
+        rwhv->SetBackgroundColor(color.value_or(SK_ColorWHITE));
     }
   } else {
     // Create one if not.