Subtree caching implementation in blink-core

Source/platform/graphics/paint/SubtreeRecorder.h

Index: Source/platform/graphics/paint/SubtreeRecorder.h
diff --git a/Source/platform/graphics/paint/SubtreeRecorder.h b/Source/platform/graphics/paint/SubtreeRecorder.h
index c27e71d967b86217cff7441049b769c6d22797b2..9bbfc539d07e9645cf0081861a2230b5abad98b6 100644
--- a/Source/platform/graphics/paint/SubtreeRecorder.h
+++ b/Source/platform/graphics/paint/SubtreeRecorder.h
@@ -17,19 +17,15 @@ class GraphicsContext;
 // for the paint phase.
 class PLATFORM_EXPORT SubtreeRecorder {
 public:
+    static bool useCachedSubtreeIfPossible(GraphicsContext&, const DisplayItemClientWrapper&, int paintPhase);
+
     SubtreeRecorder(GraphicsContext&, const DisplayItemClientWrapper&, int paintPhase);
     ~SubtreeRecorder();
 
-    bool canUseCache() const;
-
 private:
     DisplayItemList* m_displayItemList;
     DisplayItemClientWrapper m_client;
     const int m_paintPhase;
-    bool m_canUseCache;
-#if ENABLE(ASSERT)
-    mutable bool m_checkedCanUseCache;
-#endif
 };
 
 } // namespace blink