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 7749b121c85d6ee656a1e0d5eea605279727650c..b1fbafbfd1acccbfabc174f062d16ae75f9fe176 100644
--- a/Source/core/frame/FrameView.h
+++ b/Source/core/frame/FrameView.h
@@ -64,7 +64,7 @@ class LayoutScrollbarPart;
 class LayoutView;
 class ScrollingCoordinator;
 class TracedValue;
-struct CompositedSelectionBound;
+struct CompositedSelection;
 
 typedef unsigned long long DOMTimeStamp;
 
@@ -680,8 +680,8 @@ 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;