Before finalizing scroll dimensions, check again whether we need scrollbars

third_party/WebKit/Source/core/layout/LayoutBlock.cpp

Index: third_party/WebKit/Source/core/layout/LayoutBlock.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlock.cpp b/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
index 90ee7c61e648e136aaf97962698a7cf0c2a52ed5..74b1bb3c65416f3e13203ab79f13fe03fb08624c 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
@@ -864,7 +864,9 @@ void LayoutBlock::finishDelayUpdateScrollInfo()
             if (block.key->hasOverflowClip()) {
                 PaintLayerScrollableArea* scrollableArea = block.key->layer()->scrollableArea();
                 ScrollInfo& scrollInfo = block.value;
-                scrollableArea->finalizeScrollDimensions(scrollInfo.scrollOffset, scrollInfo.autoHorizontalScrollBarChanged, scrollInfo.autoVerticalScrollBarChanged);
+                bool autoHorizontalScrollBarChanged, autoVerticalScrollBarChanged;

[szager1, 2015/12/15 21:43:30]

I don't think you want new bool's here.  Instead:

scrollableArea->updateScrollDimensions(scrollInfo.scrollOffset,
scrollInfo.autoHorizontalScrollbarChanged,
scrollInfo.autoVerticalScrollbarChanged);

The logic in updateScrollDimensions should do the right thing with the bool's.

+                scrollableArea->updateScrollDimensions(scrollInfo.scrollOffset, autoHorizontalScrollBarChanged, autoVerticalScrollBarChanged);
+                scrollableArea->finalizeScrollDimensions(scrollInfo.scrollOffset, autoHorizontalScrollBarChanged || scrollInfo.autoHorizontalScrollBarChanged, autoVerticalScrollBarChanged || scrollInfo.autoVerticalScrollBarChanged);
             }
         }
     }