DCHECK that paint properties are never null

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

 // Copyright 2015 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 PaintChunker_h
 #define PaintChunker_h
 
 #include "platform/PlatformExport.h"
 #include "platform/graphics/paint/DisplayItem.h"
 #include "platform/graphics/paint/PaintChunk.h"
 #include "platform/graphics/paint/PaintChunkProperties.h"
 #include "wtf/Allocator.h"
+#include "wtf/AutoReset.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 // Accepts information about changes to |PaintChunkProperties| as drawings are
 // accumulated, and produces a series of paint chunks: contiguous ranges of the
 // display list with identical |PaintChunkProperties|.
 class PLATFORM_EXPORT PaintChunker final {
   DISALLOW_NEW();
@@ skipping 44 matching lines @@
     // Item requires its own paint chunk.
     RequiresSeparateChunk,
   };
 
   Vector<PaintChunk> m_chunks;
   Vector<ItemBehavior> m_chunkBehavior;
   Optional<PaintChunk::Id> m_currentChunkId;
   PaintChunkProperties m_currentProperties;
 };
 
+#if DCHECK_IS_ON()
+class DisableNullPaintPropertyChecks {
+  STACK_ALLOCATED();
+  WTF_MAKE_NONCOPYABLE(DisableNullPaintPropertyChecks);
+
+ public:
+  DisableNullPaintPropertyChecks();
+
+ private:
+  AutoReset<bool> m_disabler;
+};
+#endif  // DCHECK_IS_ON()
+
 }  // namespace blink
 
 #endif  // PaintChunker_h