Revert of Calculate paint invalidation rect for scrollbars

third_party/WebKit/Source/platform/scroll/ScrollbarTheme.cpp

 /*
  * Copyright (C) 2011 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 152 matching lines @@
     } else if (backButtonRect(scrollbar, BackButtonEndPart).contains(testPosition)) {
         result = BackButtonEndPart;
     } else if (forwardButtonRect(scrollbar, ForwardButtonStartPart).contains(testPosition)) {
         result = ForwardButtonStartPart;
     } else if (forwardButtonRect(scrollbar, ForwardButtonEndPart).contains(testPosition)) {
         result = ForwardButtonEndPart;
     }
     return result;
 }
 
+void ScrollbarTheme::invalidatePart(ScrollbarThemeClient* scrollbar, ScrollbarPart part)
+{
+    if (part == NoPart)
+        return;
+
+    IntRect result;
+    switch (part) {
+    case BackButtonStartPart:
+        result = backButtonRect(scrollbar, BackButtonStartPart, true);
+        break;
+    case BackButtonEndPart:
+        result = backButtonRect(scrollbar, BackButtonEndPart, true);
+        break;
+    case ForwardButtonStartPart:
+        result = forwardButtonRect(scrollbar, ForwardButtonStartPart, true);
+        break;
+    case ForwardButtonEndPart:
+        result = forwardButtonRect(scrollbar, ForwardButtonEndPart, true);
+        break;
+    case TrackBGPart:
+        result = trackRect(scrollbar, true);
+        break;
+    case ScrollbarBGPart:
+        result = scrollbar->frameRect();
+        break;
+    default: {
+        IntRect beforeThumbRect, thumbRect, afterThumbRect;
+        splitTrack(scrollbar, trackRect(scrollbar), beforeThumbRect, thumbRect, afterThumbRect);
+        if (part == BackTrackPart)
+            result = beforeThumbRect;
+        else if (part == ForwardTrackPart)
+            result = afterThumbRect;
+        else
+            result = thumbRect;
+    }
+    }
+    result.moveBy(-scrollbar->location());
+    scrollbar->invalidateRect(result);
+}
+
 void ScrollbarTheme::paintScrollCorner(GraphicsContext* context, const DisplayItemClientWrapper& displayItemClient, const IntRect& cornerRect)
 {
     if (cornerRect.isEmpty())
         return;
 
     if (DrawingRecorder::useCachedDrawingIfPossible(*context, displayItemClient, DisplayItem::ScrollbarCorner))
         return;
 
     DrawingRecorder recorder(*context, displayItemClient, DisplayItem::ScrollbarCorner, cornerRect);
 #if OS(MACOSX)
@@ skipping 149 matching lines @@
         return DisplayItem::ScrollbarBackTrack;
     case ForwardTrackPart:
         return DisplayItem::ScrollbarForwardTrack;
     default:
         ASSERT_NOT_REACHED();
         return DisplayItem::ScrollbarBackTrack;
     }
 }
 
 } // namespace blink