Improving direction-based selection strategy.

Source/core/editing/GranularityStrategy.h

Index: Source/core/editing/GranularityStrategy.h
diff --git a/Source/core/editing/GranularityStrategy.h b/Source/core/editing/GranularityStrategy.h
index 9d31bc84eb0ad41f48f7a04ea2fa49f2e994b75c..72763d0b771c8cda62cd635ce9a01b51cf64f441 100644
--- a/Source/core/editing/GranularityStrategy.h
+++ b/Source/core/editing/GranularityStrategy.h
@@ -18,7 +18,7 @@ public:
 
     // Calculates and returns the new selection based on the updated user
     // selection extent |extentPosition| and the granularity strategy.
-    virtual VisibleSelection updateExtent(const VisiblePosition& extentPosition, const VisibleSelection&) = 0;
+    virtual VisibleSelection updateExtent(const IntPoint&, LocalFrame*) = 0;
 
 protected:
     GranularityStrategy();
@@ -33,7 +33,7 @@ public:
     // GranularityStrategy:
     SelectionStrategy GetType() const final;
     void Clear() final;
-    VisibleSelection updateExtent(const VisiblePosition& extentPosition, const VisibleSelection&) final;
+    VisibleSelection updateExtent(const IntPoint&, LocalFrame*) final;
 };
 
 // "Expand by word, shrink by character" selection strategy.
@@ -48,7 +48,7 @@ public:
     // GranularityStrategy:
     SelectionStrategy GetType() const final;
     void Clear() final;
-    VisibleSelection updateExtent(const VisiblePosition&, const VisibleSelection&) final;
+    VisibleSelection updateExtent(const IntPoint&, LocalFrame*) final;
 
 private:
     enum class BoundAdjust {CurrentPosIfOnBound, NextBoundIfOnBound};
@@ -65,6 +65,8 @@ private:
     // Set to true if the selection was shrunk (without changing relative
     // base/extent order) as a result of the most recent updateExtent call.
     bool m_lastMoveShrunkSelection;
+    IntPoint m_extentPoint;
+    int m_offset;
 };
 
 } // namespace blink