Clear scrollbar damages in time

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index b1239206822ae5264809d81cf307f7e4b542dff4..721428684de0b3e23379d32242f20faf1f320717 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -1569,6 +1569,19 @@ void RenderBox::invalidatePaintIfNeeded(const PaintInvalidationState& paintInval
     setPreviousPaintInvalidationRect(boundsRectForPaintInvalidation(&newPaintInvalidationContainer, &paintInvalidationState));
     setPreviousPositionFromPaintInvalidationContainer(RenderLayer::positionFromPaintInvalidationContainer(this, &newPaintInvalidationContainer, &paintInvalidationState));
 
+    // Issue paint invalidations for any scrollbars if there is a scrollable area for this renderer.
+    if (enclosingLayer()) {
+        if (RenderLayerScrollableArea* area = enclosingLayer()->scrollableArea()) {
+            if (!view()->doingFullRepaint()) {

[dsinclair, 2014/07/22 19:55:22]

This is really confusing. I wonder if the resetScrollbarDamage shouldn't
actually be happening inside the clearPaintInvalidationState() method instead of
being done in here.

Then this chunk would stay after the invalidatePaintINeeded call.

[Xianzhu, 2014/07/23 00:18:13]

Done.

+                if (area->hasVerticalBarDamage())
+                    invalidatePaintRectangle(area->verticalBarDamage());
+                if (area->hasHorizontalBarDamage())
+                    invalidatePaintRectangle(area->horizontalBarDamage());
+            }
+            area->resetScrollbarDamage();
+        }
+    }
+
     // If we are set to do a full paint invalidation that means the RenderView will be
     // issue paint invalidations. We can then skip issuing of paint invalidations for the child
     // renderers as they'll be covered by the RenderView.
@@ -1585,16 +1598,6 @@ void RenderBox::invalidatePaintIfNeeded(const PaintInvalidationState& paintInval
     if (!RenderObject::invalidatePaintIfNeeded(newPaintInvalidationContainer, oldPaintInvalidationRect, oldPositionFromPaintInvalidationContainer, paintInvalidationState))
         invalidatePaintForOverflowIfNeeded();
 
-    // Issue paint invalidations for any scrollbars if there is a scrollable area for this renderer.
-    if (enclosingLayer()) {
-        if (RenderLayerScrollableArea* area = enclosingLayer()->scrollableArea()) {
-            if (area->hasVerticalBarDamage())
-                invalidatePaintRectangle(area->verticalBarDamage());
-            if (area->hasHorizontalBarDamage())
-                invalidatePaintRectangle(area->horizontalBarDamage());
-            area->resetScrollbarDamage();
-        }
-    }
 }
 
 bool RenderBox::pushContentsClip(PaintInfo& paintInfo, const LayoutPoint& accumulatedOffset, ContentsClipBehavior contentsClipBehavior)