Enhance chrome.app.window API with window background color

extensions/components/native_app_window/native_app_window_views.cc

Index: extensions/components/native_app_window/native_app_window_views.cc
diff --git a/extensions/components/native_app_window/native_app_window_views.cc b/extensions/components/native_app_window/native_app_window_views.cc
index f4abafac3c9ae2539b15b033ee1fbf5682effa73..ff1df9580810f8792b2de213df71d5a6c986b213 100644
--- a/extensions/components/native_app_window/native_app_window_views.cc
+++ b/extensions/components/native_app_window/native_app_window_views.cc
@@ -291,11 +291,14 @@ void NativeAppWindowViews::OnWidgetActivationChanged(views::Widget* widget,
 
 void NativeAppWindowViews::RenderViewCreated(
     content::RenderViewHost* render_view_host) {
+  content::RenderWidgetHostView* view =
+      render_view_host->GetWidget()->GetView();
+  DCHECK(view);
+
   if (app_window_->requested_alpha_enabled() && CanHaveAlphaEnabled()) {
-    content::RenderWidgetHostView* view =
-        render_view_host->GetWidget()->GetView();
-    DCHECK(view);
     view->SetBackgroundColor(SK_ColorTRANSPARENT);

[Reilly Grant (use Gerrit), 2017/03/10 18:39:18]

This implies that background color and alpha are mutually exclusive. This should
be documented in the IDL.

+  } else if (app_window_->backgroundColor() != SK_ColorWHITE) {
+    view->SetBackgroundColor(app_window_->backgroundColor());
   }
 }