Plumbs through support for painting the scrollbarcorner

ui/native_theme/native_theme_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/native_theme/native_theme_win.h"
 
 #include <windows.h>
 #include <uxtheme.h>
 #include <vsstyle.h>
 #include <vssym32.h>
@@ skipping 436 matching lines @@
     case kScrollbarUpArrow:
     case kScrollbarLeftArrow:
     case kScrollbarRightArrow:
       PaintScrollbarArrow(hdc, part, state, rect, extra.scrollbar_arrow);
       break;
     case kScrollbarHorizontalTrack:
     case kScrollbarVerticalTrack:
       PaintScrollbarTrack(canvas, hdc, part, state, rect,
                           extra.scrollbar_track);
       break;
+    case kScrollbarCorner:
+      canvas->drawColor(SK_ColorWHITE, SkXfermode::kSrc_Mode);
+      break;
     case kScrollbarHorizontalThumb:
     case kScrollbarVerticalThumb:
     case kScrollbarHorizontalGripper:
     case kScrollbarVerticalGripper:
       PaintScrollbarThumb(hdc, part, state, rect, extra.scrollbar_thumb);
       break;
     case kInnerSpinButton:
       PaintSpinButton(hdc, part, state, rect, extra.inner_spin);
       break;
     case kTrackbarThumb:
@@ skipping 1625 matching lines @@
     handle = open_theme_(NULL, L"Spin");
     break;
   default:
     NOTREACHED();
   }
   theme_handles_[theme_name] = handle;
   return handle;
 }
 
 }  // namespace ui