Merge 154135 "Only set up scroll bar layers if we have created t..."

Source/core/page/scrolling/ScrollingCoordinator.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 263 matching lines @@
     GraphicsLayer* scrollLayer = scrollLayerForScrollableArea(scrollableArea);
     if (scrollLayer)
         scrollLayer->setScrollableArea(scrollableArea);
 
     WebLayer* webLayer = scrollingWebLayerForScrollableArea(scrollableArea);
     if (webLayer) {
         webLayer->setScrollable(true);
         webLayer->setScrollPosition(IntPoint(scrollableArea->scrollPosition() - scrollableArea->minimumScrollPosition()));
         webLayer->setMaxScrollPosition(IntSize(scrollableArea->scrollSize(HorizontalScrollbar), scrollableArea->scrollSize(VerticalScrollbar)));
     }
-    if (WebScrollbarLayer* scrollbarLayer = getWebScrollbarLayer(scrollableArea, HorizontalScrollbar))
-        setupScrollbarLayer(horizontalScrollbarLayerForScrollableArea(scrollableArea), scrollbarLayer, webLayer);
-    if (WebScrollbarLayer* scrollbarLayer = getWebScrollbarLayer(scrollableArea, VerticalScrollbar))
-        setupScrollbarLayer(verticalScrollbarLayerForScrollableArea(scrollableArea), scrollbarLayer, webLayer);
+    if (WebScrollbarLayer* scrollbarLayer = getWebScrollbarLayer(scrollableArea, HorizontalScrollbar)) {
+        GraphicsLayer* horizontalScrollbarLayer = horizontalScrollbarLayerForScrollableArea(scrollableArea);
+        if (horizontalScrollbarLayer)
+            setupScrollbarLayer(horizontalScrollbarLayer, scrollbarLayer, webLayer);
+    }
+    if (WebScrollbarLayer* scrollbarLayer = getWebScrollbarLayer(scrollableArea, VerticalScrollbar)) {
+        GraphicsLayer* verticalScrollbarLayer = verticalScrollbarLayerForScrollableArea(scrollableArea);
+        if (verticalScrollbarLayer)
+            setupScrollbarLayer(verticalScrollbarLayer, scrollbarLayer, webLayer);
+    }
 }
 
 void ScrollingCoordinator::setTouchEventTargetRects(const Vector<IntRect>& absoluteHitTestRects)
 {
     if (WebLayer* scrollLayer = scrollingWebLayerForScrollableArea(m_page->mainFrame()->view())) {
         WebVector<WebRect> webRects(absoluteHitTestRects.size());
         for (size_t i = 0; i < absoluteHitTestRects.size(); ++i)
             webRects[i] = absoluteHitTestRects[i];
         scrollLayer->setTouchEventHandlerRegion(webRects);
     }
@@ skipping 336 matching lines @@
         stringBuilder.resize(stringBuilder.length() - 2);
     return stringBuilder.toString();
 }
 
 String ScrollingCoordinator::mainThreadScrollingReasonsAsText() const
 {
     return mainThreadScrollingReasonsAsText(mainThreadScrollingReasons());
 }
 
 } // namespace WebCore