Plumb selection bounds as a single unit

public/platform/WebLayerTreeView.h

Index: public/platform/WebLayerTreeView.h
diff --git a/public/platform/WebLayerTreeView.h b/public/platform/WebLayerTreeView.h
index bcc5f1e858d19d0aecc2c98df715b938dc137bec..8822d9ce867d847cd317de1fb98deca84e6fca4b 100644
--- a/public/platform/WebLayerTreeView.h
+++ b/public/platform/WebLayerTreeView.h
@@ -31,6 +31,7 @@
 #include "WebFloatPoint.h"
 #include "WebNonCopyable.h"
 #include "WebPrivateOwnPtr.h"
+#include "WebSelectionBounds.h"
 #include "WebSize.h"
 #include "WebTopControlsState.h"
 
@@ -41,7 +42,6 @@ namespace blink {
 class WebCompositeAndReadbackAsyncCallback;
 class WebLayer;
 struct WebPoint;
-struct WebSelectionBound;
 class WebWidget;
 
 class WebLayerTreeView {
@@ -133,7 +133,9 @@ public:
     // If the (empty) selection is an insertion point, |start| and |end| will be identical with type |Caret|.
     // If the (non-empty) selection has mixed RTL/LTR text, |start| and |end| may share the same type,
     // |SelectionLeft| or |SelectionRight|.
+    // FIXME: Remove this overload when downstream consumers have been updated to use WebSelectionBounds, crbug.com/466672.
     virtual void registerSelection(const WebSelectionBound& start, const WebSelectionBound& end) { }
+    virtual void registerSelection(const WebSelectionBounds& bounds) { registerSelection(bounds.start, bounds.end); }
     virtual void clearSelection() { }
 
     // Debugging / dangerous ---------------------------------------------