Introduce SelectionAdjuster to adjust selections between DOM tree version and composed tree version

third_party/WebKit/Source/core/editing/VisibleSelection.h

Index: third_party/WebKit/Source/core/editing/VisibleSelection.h
diff --git a/third_party/WebKit/Source/core/editing/VisibleSelection.h b/third_party/WebKit/Source/core/editing/VisibleSelection.h
index 2a678279ed7fe7e8c0241e62f86c6ca88c6c70fc..9ece79726d5d6c2095e350c96e878dd7c410c4c4 100644
--- a/third_party/WebKit/Source/core/editing/VisibleSelection.h
+++ b/third_party/WebKit/Source/core/editing/VisibleSelection.h
@@ -39,6 +39,7 @@
 namespace blink {
 
 class LayoutPoint;
+class SelectionAdjuster;
 
 // TODO(yosin) We should use capitalized name instead of |SEL_DEFAULT_AFFINITY|.
 const TextAffinity SEL_DEFAULT_AFFINITY = TextAffinity::Downstream; // NOLINT
@@ -74,8 +75,6 @@ public:
 
     explicit VisibleSelectionTemplate(const PositionWithAffinityTemplate<Strategy>&, bool isDirectional = false);
 
-    static VisibleSelectionTemplate<Strategy> createWithoutValidation(const PositionTemplate<Strategy>& base, const PositionTemplate<Strategy>& extent, const PositionTemplate<Strategy>& start, const PositionTemplate<Strategy>& end, TextAffinity, bool isDirectional);
-
     VisibleSelectionTemplate(const VisibleSelectionTemplate&);
     VisibleSelectionTemplate& operator=(const VisibleSelectionTemplate&);
 
@@ -165,7 +164,7 @@ public:
     void setEndRespectingGranularity(TextGranularity, EWordSide = RightWordIfOnBoundary);
 
 private:
-    VisibleSelectionTemplate(const PositionTemplate<Strategy>& base, const PositionTemplate<Strategy>& extent, const PositionTemplate<Strategy>& start, const PositionTemplate<Strategy>& end, TextAffinity, bool isDirectional);
+    friend class SelectionAdjuster;
 
     void validate(TextGranularity = CharacterGranularity);
 
@@ -207,6 +206,16 @@ extern template class CORE_EXTERN_TEMPLATE_EXPORT VisibleSelectionTemplate<Editi
 using VisibleSelection = VisibleSelectionTemplate<EditingStrategy>;
 using VisibleSelectionInComposedTree = VisibleSelectionTemplate<EditingInComposedTreeStrategy>;
 
+// TODO(yosin): We should move |SelectionAdjuster| to its own file.
+class SelectionAdjuster final {
+    STATIC_ONLY(SelectionAdjuster);
+public:
+    static void adjustSelectionInComposedTree(VisibleSelectionInComposedTree*, const VisibleSelection&);
+    static void adjustSelectionInDOMTree(VisibleSelection*, const VisibleSelectionInComposedTree&);
+    static void adjustSelectionToAvoidCrossingShadowBoundaries(VisibleSelection*);
+    static void adjustSelectionToAvoidCrossingShadowBoundaries(VisibleSelectionInComposedTree*);
+};
+
 // TODO(yosin): We should use |operator==()| instead of
 // |equalSelectionsInDOMTree()|.
 bool equalSelectionsInDOMTree(const VisibleSelection&, const VisibleSelection&);