Fix scrollbar buttons in classic windows theme. When I refactored the code

ui/gfx/native_theme_win.cc

 // Copyright (c) 2011 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/gfx/native_theme_win.h"
 
 #include <windows.h>
 #include <uxtheme.h>
 #include <vsstyle.h>
 #include <vssym32.h>
@@ skipping 243 matching lines @@
           break;
         default:
           NOTREACHED() << "Invalid part: " << part;
           break;
       }
     }
 
     return draw_theme_(handle, hdc, SBP_ARROWBTN, state_id, &rect_win, NULL);
   }
 
-  // TODO: Draw it manually.
-  DrawFrameControl(hdc, &rect_win, DFC_SCROLL, 0);
+  int classic_state = DFCS_SCROLLDOWN;
+  switch(part) {
+    case kScrollbarDownArrow:
+      classic_state = DFCS_SCROLLDOWN;
+      break;
+    case kScrollbarLeftArrow:
+      classic_state = DFCS_SCROLLLEFT;
+      break;
+    case kScrollbarRightArrow:
+      classic_state = DFCS_SCROLLRIGHT;
+      break;
+    case kScrollbarUpArrow:
+      classic_state = DFCS_SCROLLUP;
+      break;
+    default:
+      NOTREACHED() << "Invalid part: " << part;
+      break;
+  }
+
+  DrawFrameControl(hdc, &rect_win, DFC_SCROLL, classic_state);
   return S_OK;
 }
 
 HRESULT NativeThemeWin::PaintScrollbarTrack(
     SkCanvas* canvas,
     HDC hdc,
     Part part,
     State state,
     const gfx::Rect& rect,
     const ScrollbarTrackExtraParams& extra) const {
@@ skipping 1231 matching lines @@
       }
       break;
     default:
       NOTREACHED() << "Invalid part: " << part;
       break;
   }
   return state_id;
 }
 
 }  // namespace gfx