Plumb selection bounds as a single unit

Source/core/frame/FrameView.h

Index: Source/core/frame/FrameView.h
diff --git a/Source/core/frame/FrameView.h b/Source/core/frame/FrameView.h
index b67fcabb358feff80575a0af8fabe4fcd7ddca1d..d697788a867de8af5f847df075243935581beba2 100644
--- a/Source/core/frame/FrameView.h
+++ b/Source/core/frame/FrameView.h
@@ -61,7 +61,7 @@ class LayoutObject;
 class LayoutScrollbarPart;
 class LayoutView;
 class ScrollingCoordinator;
-struct CompositedSelectionBound;
+struct CompositedSelection;
 
 typedef unsigned long long DOMTimeStamp;
 
@@ -670,8 +670,8 @@ private:
 
     void updateLayersAndCompositingAfterScrollIfNeeded();
 
-    static bool computeCompositedSelectionBounds(LocalFrame&, CompositedSelectionBound& start, CompositedSelectionBound& end);
-    void updateCompositedSelectionBoundsIfNeeded();
+    static bool computeCompositedSelection(LocalFrame&, CompositedSelection&);
+    void updateCompositedSelectionIfNeeded();
 
     // Returns true if the FrameView's own scrollbars overlay its content when visible.
     bool hasOverlayScrollbars() const;