Allow the native theme to paint the corner between scrollbars

ui/native_theme/native_theme_base.cc

Index: ui/native_theme/native_theme_base.cc
diff --git a/ui/native_theme/native_theme_base.cc b/ui/native_theme/native_theme_base.cc
index 1272af7ecd19040b1f91e1c0cd15d4a94b168b7e..b839621b202ebc4448d42e645403eaaf4e1d6b19 100644
--- a/ui/native_theme/native_theme_base.cc
+++ b/ui/native_theme/native_theme_base.cc
@@ -519,11 +519,6 @@ void NativeThemeBase::PaintScrollbarThumb(SkCanvas* canvas,
 void NativeThemeBase::PaintScrollbarCorner(SkCanvas* canvas,
                                            State state,
                                            const gfx::Rect& rect) const {
-  SkPaint paint;
-  paint.setColor(SK_ColorWHITE);
-  paint.setStyle(SkPaint::kFill_Style);
-  paint.setXfermodeMode(SkXfermode::kSrc_Mode);
-  canvas->drawIRect(RectToSkIRect(rect), paint);
 }
 
 void NativeThemeBase::PaintCheckbox(SkCanvas* canvas,