Make FrameCaret to utilize SynchronousMutationObserver

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

 /*
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  * are met:
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  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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 #ifndef FrameCaret_h
 #define FrameCaret_h
 
 #include "core/CoreExport.h"
+#include "core/dom/SynchronousMutationObserver.h"
 #include "core/editing/PositionWithAffinity.h"
 #include "platform/Timer.h"
 #include "platform/geometry/LayoutRect.h"
 #include "platform/heap/GarbageCollected.h"
 #include "platform/heap/Member.h"
 #include <memory>
 
 namespace blink {
 
 class CaretBase;
 class CharacterData;
 class DisplayItemClient;
 class Document;
 class GraphicsContext;
 class Node;
 class LocalFrame;
 class SelectionEditor;
 
 enum class CaretVisibility { Visible, Hidden };
 
 class CORE_EXPORT FrameCaret final
-    : public GarbageCollectedFinalized<FrameCaret> {
+    : public GarbageCollectedFinalized<FrameCaret>,
+      public SynchronousMutationObserver {
+  USING_GARBAGE_COLLECTED_MIXIN(FrameCaret);
+
  public:
   FrameCaret(LocalFrame&, const SelectionEditor&);
   ~FrameCaret();
 
   const DisplayItemClient& displayItemClient() const;
   bool isActive() const { return caretPosition().isNotNull(); }
 
+  void documentAttached(Document*);
   void updateAppearance();
 
   // Used to suspend caret blinking while the mouse is down.
   void setCaretBlinkingSuspended(bool suspended) {
     m_isCaretBlinkingSuspended = suspended;
   }
   bool isCaretBlinkingSuspended() const { return m_isCaretBlinkingSuspended; }
   void stopCaretBlinkTimer();
   void startBlinkCaret();
 
   void setCaretVisibility(CaretVisibility);
   void setCaretRectNeedsUpdate();
   // If |forceInvalidation| is true the caret's previous and new rectangles
   // are forcibly invalidated regardless of the state of the blink timer.
   void invalidateCaretRect(bool forceInvalidation);
   IntRect absoluteCaretBounds() const;
 
   bool shouldShowBlockCursor() const { return m_shouldShowBlockCursor; }
   void setShouldShowBlockCursor(bool);
 
   void paintCaret(GraphicsContext&, const LayoutPoint&);
 
   void dataWillChange(const CharacterData&);
-  void nodeWillBeRemoved(Node&);
-
-  void documentDetached();
 
   // For unittests
   bool shouldPaintCaretForTesting() const { return m_shouldPaintCaret; }
   bool isPreviousCaretDirtyForTesting() const { return m_previousCaretNode; }
 
   DECLARE_TRACE();
 
  private:
   friend class FrameSelectionTest;
 
   const PositionWithAffinity caretPosition() const;
 
   bool shouldBlinkCaret() const;
   void caretBlinkTimerFired(TimerBase*);
   bool caretPositionIsValidForDocument(const Document&) const;
 
+  // Implementation of |SynchronousMutationObserver| member functions.
+  void contextDestroyed(Document*) final;
+  void nodeWillBeRemoved(Node&) final;
+
   const Member<const SelectionEditor> m_selectionEditor;
   const Member<LocalFrame> m_frame;
   const std::unique_ptr<CaretBase> m_caretBase;
   // The last node which painted the caret. Retained for clearing the old
   // caret when it moves.
   Member<Node> m_previousCaretNode;
   Member<Node> m_previousCaretAnchorNode;
   LayoutRect m_previousCaretRect;
   CaretVisibility m_caretVisibility;
   CaretVisibility m_previousCaretVisibility;
   // TODO(https://crbug.com/668758): Consider using BeginFrame update for this.
   TaskRunnerTimer<FrameCaret> m_caretBlinkTimer;
   bool m_caretRectDirty : 1;
   bool m_shouldPaintCaret : 1;
   bool m_isCaretBlinkingSuspended : 1;
   bool m_shouldShowBlockCursor : 1;
 };
 
 }  // namespace blink
 
 #endif  // FrameCaret_h