Move VisibleSelection::ChangeObserver out from VisibleSelection class

Source/core/editing/VisibleSelection.h

 /*
  * Copyright (C) 2004 Apple Computer, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 26 matching lines @@
 #include "wtf/Allocator.h"
 
 namespace blink {
 
 class LayoutPoint;
 
 // TODO(yosin) We should use capitalized name instead of |SEL_DEFAULT_AFFINITY|.
 const TextAffinity SEL_DEFAULT_AFFINITY = TextAffinity::Downstream; // NOLINT
 enum SelectionDirection { DirectionForward, DirectionBackward, DirectionRight, DirectionLeft };
 
+// Listener of |VisibleSelection| modification. |didChangeVisibleSelection()|
+// will be invoked when base, extent, start or end is moved to a different
+// position.
+//
+// Objects implementing |VisibleSelectionChangeObserver| interface must outlive
+// the |VisibleSelection| object.
+class CORE_EXPORT VisibleSelectionChangeObserver : public WillBeGarbageCollectedMixin {
+    WTF_MAKE_NONCOPYABLE(VisibleSelectionChangeObserver);
+public:
+    VisibleSelectionChangeObserver();
+    virtual ~VisibleSelectionChangeObserver();
+    virtual void didChangeVisibleSelection() = 0;
+    DEFINE_INLINE_VIRTUAL_TRACE() { }
+};
+
 class CORE_EXPORT VisibleSelection {
     DISALLOW_ALLOCATION();
     DECLARE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(VisibleSelection);
 public:
     class InDOMTree {
         STATIC_ONLY(InDOMTree);
     public:
         using PositionType = Position;
         using Strategy = EditingStrategy;
 
@@ skipping 110 matching lines @@
     // ShadowRoot node for new shadow trees, or 0 for non-shadow trees.
     Node* nonBoundaryShadowTreeRootNode() const;
 
     VisiblePosition visiblePositionRespectingEditingBoundary(const LayoutPoint& localPoint, Node* targetNode) const;
     PositionWithAffinity positionRespectingEditingBoundary(const LayoutPoint& localPoint, Node* targetNode) const;
 
     bool isValidFor(const Document&) const;
     void setWithoutValidation(const Position&, const Position&);
     void setWithoutValidation(const PositionInComposedTree&, const PositionInComposedTree&);
 
-    // Listener of VisibleSelection modification. didChangeVisibleSelection() will be invoked when base, extent, start
-    // or end is moved to a different position.
-    //
-    // Objects implementing |ChangeObserver| interface must outlive the VisibleSelection object.
-    class CORE_EXPORT ChangeObserver : public WillBeGarbageCollectedMixin {
-        WTF_MAKE_NONCOPYABLE(ChangeObserver);
-    public:
-        ChangeObserver();
-        virtual ~ChangeObserver();
-        virtual void didChangeVisibleSelection() = 0;
-        DEFINE_INLINE_VIRTUAL_TRACE() { }
-    };
-
-    void setChangeObserver(ChangeObserver&);
+    void setChangeObserver(VisibleSelectionChangeObserver&);
     void clearChangeObserver();
     void didChange(); // Fire the change observer, if any.
 
     DECLARE_TRACE();
 
     void validatePositionsIfNeeded();
 
 #ifndef NDEBUG
     void debugPosition(const char* message) const;
     void formatForDebugger(char* buffer, unsigned length) const;
@@ skipping 34 matching lines @@
     // VisibleUnit.cpp, and VisiblePosition.cpp). We'll do that in the future.
     PositionInComposedTree m_baseInComposedTree;
     PositionInComposedTree m_extentInComposedTree;
     PositionInComposedTree m_startInComposedTree;
     PositionInComposedTree m_endInComposedTree;
 
     TextAffinity m_affinity; // the upstream/downstream affinity of the caret
 
     // Oilpan: this reference has a lifetime that is at least as long
     // as this object.
-    RawPtrWillBeMember<ChangeObserver> m_changeObserver;
+    RawPtrWillBeMember<VisibleSelectionChangeObserver> m_changeObserver;
 
     // these are cached, can be recalculated by validate()
     SelectionType m_selectionType; // None, Caret, Range
     bool m_baseIsFirst : 1; // True if base is before the extent
     bool m_isDirectional : 1; // Non-directional ignores m_baseIsFirst and selection always extends on shift + arrow key.
 };
 
 // We don't yet support multi-range selections, so we only ever have one range
 // to return.
 CORE_EXPORT PassRefPtrWillBeRawPtr<Range> firstRangeOf(const VisibleSelection&);
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showTree(const blink::VisibleSelection&);
 void showTree(const blink::VisibleSelection*);
 #endif
 
 #endif // VisibleSelection_h