Templatize version updateSelectionForMouseDrag in SelectionController

Source/core/editing/SelectionController.h

Index: Source/core/editing/SelectionController.h
diff --git a/Source/core/editing/SelectionController.h b/Source/core/editing/SelectionController.h
index 9af726f18e07affd2074fe82f22e3badd61f64e4..980fe65b89aceaa1f24f2781a1c1f0a03e4e0270 100644
--- a/Source/core/editing/SelectionController.h
+++ b/Source/core/editing/SelectionController.h
@@ -68,6 +68,9 @@ public:
 private:
     explicit SelectionController(LocalFrame&);
 
+    template <typename Strategy>
+    void updateSelectionForMouseDragAlgorithm(const HitTestResult&, Node*, const LayoutPoint&, const IntPoint&);
+
     enum AppendTrailingWhitespace { ShouldAppendTrailingWhitespace, DontAppendTrailingWhitespace };
     void selectClosestWordFromHitTestResult(const HitTestResult&, AppendTrailingWhitespace);
     void selectClosestMisspellingFromHitTestResult(const HitTestResult&, AppendTrailingWhitespace);