Optimize CompositingRecorder::endCompositing to not need an SkPictureBuilder

third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef DrawingRecorder_h
 #define DrawingRecorder_h
 
 #include "platform/PlatformExport.h"
 
 #include "platform/geometry/FloatRect.h"
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/graphics/paint/DrawingDisplayItem.h"
 #include "platform/graphics/paint/PaintController.h"
 #include "wtf/Allocator.h"
+#include "wtf/AutoReset.h"
 #include "wtf/Noncopyable.h"
 
 #ifndef NDEBUG
 #include "wtf/text/WTFString.h"
 #endif
 
 namespace blink {
 
 class GraphicsContext;
 
@@ skipping 22 matching lines @@
 
  private:
   GraphicsContext& m_context;
   const DisplayItemClient& m_displayItemClient;
   const DisplayItem::Type m_displayItemType;
 
   // True if there are no transparent areas. Only used for SlimmingPaintV2.
   bool m_knownToBeOpaque;
 
 #if DCHECK_IS_ON()
-  size_t m_displayItemPosition;
+  // Ensures the list size does not change during the recorder's scope.
+  size_t m_initialDisplayItemListSize;
 #endif
 };
 
+#if DCHECK_IS_ON()
+class DisableListModificationCheck {
+  STACK_ALLOCATED();
+  WTF_MAKE_NONCOPYABLE(DisableListModificationCheck);
+
+ public:
+  DisableListModificationCheck();
+
+ private:
+  AutoReset<bool> m_disabler;
+};
+#endif  // DCHECK_IS_ON()
+
 }  // namespace blink
 
 #endif  // DrawingRecorder_h