Make CaretBase a DisplayItemClient.

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

Index: third_party/WebKit/Source/core/editing/FrameSelection.h
diff --git a/third_party/WebKit/Source/core/editing/FrameSelection.h b/third_party/WebKit/Source/core/editing/FrameSelection.h
index 55710319706c7243216f9eb46691f2b372b90101..3761dda5677f206e7915eee5a6eb17cc815d240e 100644
--- a/third_party/WebKit/Source/core/editing/FrameSelection.h
+++ b/third_party/WebKit/Source/core/editing/FrameSelection.h
@@ -187,7 +187,7 @@ public:
     bool isCaretBoundsDirty() const;
     void setCaretRectNeedsUpdate();
     void scheduleVisualUpdate() const;
-    void invalidateCaretRect();
+    void invalidateCaretRect(bool forceInvalidation = false);
     void paintCaret(GraphicsContext&, const LayoutPoint&);
 
     // Used to suspend caret blinking while the mouse is down.
@@ -246,6 +246,8 @@ public:
 
 private:
     friend class FrameSelectionTest;
+    friend class PaintControllerPaintTestForSlimmingPaintV1AndV2;
+    FRIEND_TEST_ALL_PREFIXES(PaintControllerPaintTestForSlimmingPaintV1AndV2, FullDocumentPaintingWithCaret);
 
     explicit FrameSelection(LocalFrame*);