Add more specific metrics for main thread scrolling reasons

third_party/WebKit/Source/core/layout/compositing/CompositingRequirementsUpdater.h

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 #ifndef CompositingRequirementsUpdater_h
 #define CompositingRequirementsUpdater_h
 
+#include "core/page/scrolling/ScrollingCoordinator.h"

[bokan, 2016/12/14 13:28:58]

Forward declare rather than include.

[yigu, 2016/12/14 21:17:33]

Done.

 #include "platform/geometry/IntRect.h"
 #include "platform/graphics/CompositingReasons.h"
 #include "wtf/Allocator.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class CompositingReasonFinder;
 class PaintLayer;
 class LayoutView;
@@ skipping 10 matching lines @@
   //  For the z-order children of a compositing layer:
   //      If a child layers has a compositing layer, then all subsequent layers
   //      must be compositing in order to render above that layer.
   //
   //      If a child in the negative z-order list is compositing, then the layer
   //      itself must be compositing so that its contents render over that
   //      child.  This implies that its positive z-index children must also be
   //      compositing.
   //
   void update(PaintLayer* root);
+  void updateMainThreadScrollingReasonsFromStyle(const PaintLayer*,
+                                                 ScrollingCoordinator*) const;
 
  private:
   class OverlapMap;
   class RecursionData;
 
   void updateRecursive(PaintLayer* ancestorLayer,
                        PaintLayer* currentLayer,
                        OverlapMap&,
                        RecursionData&,
                        bool& descendantHas3DTransform,
                        Vector<PaintLayer*>& unclippedDescendants,
                        IntRect& absoluteDescendantBoundingBox);
 
   LayoutView& m_layoutView;
   CompositingReasonFinder& m_compositingReasonFinder;
 };
 
 }  // namespace blink
 
 #endif  // CompositingRequirementsUpdater_h