[SPv2] Defer decision of raster invalidation after paint for changes z-index, transform, etc.

third_party/WebKit/Source/platform/graphics/paint/PaintArtifact.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 PaintArtifact_h
 #define PaintArtifact_h
 
 #include "platform/PlatformExport.h"
 #include "platform/graphics/paint/DisplayItemList.h"
 #include "platform/graphics/paint/PaintChunk.h"
@@ skipping 31 matching lines @@
     PaintArtifact& operator=(PaintArtifact&&);
 
     bool isEmpty() const { return m_displayItemList.isEmpty(); }
 
     DisplayItemList& getDisplayItemList() { return m_displayItemList; }
     const DisplayItemList& getDisplayItemList() const { return m_displayItemList; }
 
     Vector<PaintChunk>& paintChunks() { return m_paintChunks; }
     const Vector<PaintChunk>& paintChunks() const { return m_paintChunks; }
 
-    Vector<PaintChunk>::const_iterator findChunkByDisplayItemIndex(size_t) const;
+    Vector<PaintChunk>::const_iterator findChunkByDisplayItemIndex(size_t index) const { return findChunkInVectorByDisplayItemIndex(m_paintChunks, index); }

[chrishtr, 2016/09/06 22:14:12]

Why does this call site not need:

 DCHECK(chunk != m_chunks.end());

[Xianzhu, 2016/09/06 22:42:38]

It's not obvious from the function return type that the returned value is never
m_paintChunks.end(), so I loosed the restriction here to allow not-found
situation. Then the caller should check the result if it can ensure a chunk must
be found with the given index.

 
     bool isSuitableForGpuRasterization() const { return m_isSuitableForGpuRasterization; }
 
     // Resets to an empty paint artifact.
     void reset();
 
     // Returns the approximate memory usage, excluding memory likely to be
     // shared with the embedder after copying to WebDisplayItemList.
     size_t approximateUnsharedMemoryUsage() const;
 
     // Draws the paint artifact to a GraphicsContext.
     void replay(GraphicsContext&) const;
 
     // Writes the paint artifact into a WebDisplayItemList.
     void appendToWebDisplayItemList(WebDisplayItemList*) const;
 
 private:
     DisplayItemList m_displayItemList;
     Vector<PaintChunk> m_paintChunks;
     bool m_isSuitableForGpuRasterization;
 };
 
 } // namespace blink
 
 #endif // PaintArtifact_h