win: Work on reducing number of style plugin warnings.

ui/views/test/test_views_delegate.h

Index: ui/views/test/test_views_delegate.h
diff --git a/ui/views/test/test_views_delegate.h b/ui/views/test/test_views_delegate.h
index 556ddc701daf974347285a0bc8da3727c3fb4a60..022da9a07f4ac83e9e40d55e4b9938962d32010f 100644
--- a/ui/views/test/test_views_delegate.h
+++ b/ui/views/test/test_views_delegate.h
@@ -37,7 +37,7 @@ class TestViewsDelegate : public ViewsDelegate {
 
   // ViewsDelegate:
 #if defined(OS_WIN)
-  HICON GetSmallWindowIcon() const override { return nullptr; }
+  HICON GetSmallWindowIcon() const override;
 #endif
   void OnBeforeWidgetInit(Widget::InitParams* params,
                           internal::NativeWidgetDelegate* delegate) override;