Replace RefPtrs with raw pointers (imageFromNode in Editor.cpp)

third_party/WebKit/Source/core/html/HTMLCanvasElement.h

 /*
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 114 matching lines @@
     void paint(GraphicsContext&, const LayoutRect&);
 
     SkCanvas* drawingCanvas() const;
     void disableDeferral(DisableDeferralReason) const;
     SkCanvas* existingDrawingCanvas() const;
 
     CanvasRenderingContext* renderingContext() const { return m_context.get(); }
 
     void ensureUnacceleratedImageBuffer();
     ImageBuffer* buffer() const;
-    PassRefPtr<Image> copiedImage(SourceDrawingBuffer, AccelerationHint) const;
+    Image* copiedImage(SourceDrawingBuffer, AccelerationHint) const;
     void clearCopiedImage();
 
     SecurityOrigin* getSecurityOrigin() const;
     bool originClean() const;
     void setOriginTainted() { m_originClean = false; }
 
     AffineTransform baseTransform() const;
 
     bool is3D() const;
     bool isAnimated2D() const;
@@ skipping 85 matching lines @@
     bool shouldUseDisplayList(const IntSize& deviceSize);
 
     void setSurfaceSize(const IntSize&);
 
     bool paintsIntoCanvasBuffer() const;
 
     ImageData* toImageData(SourceDrawingBuffer, SnapshotReason) const;
 
     String toDataURLInternal(const String& mimeType, const double& quality, SourceDrawingBuffer) const;
 
+    Image* ensureTransparentImage() const;
+
     HeapHashSet<WeakMember<CanvasDrawListener>> m_listeners;
 
     IntSize m_size;
 
     Member<CanvasRenderingContext> m_context;
 
     bool m_ignoreReset;
     FloatRect m_dirtyRect;
 
     mutable intptr_t m_externallyAllocatedMemory;
 
     bool m_originClean;
 
     // It prevents HTMLCanvasElement::buffer() from continuously re-attempting to allocate an imageBuffer
     // after the first attempt failed.
     mutable bool m_didFailToCreateImageBuffer;
     bool m_imageBufferIsClear;
     std::unique_ptr<ImageBuffer> m_imageBuffer;
 
     mutable RefPtr<Image> m_copiedImage; // FIXME: This is temporary for platforms that have to copy the image buffer to render (and for CSSCanvasValue).
 
     // Used for OffscreenCanvas that controls this HTML canvas element
     std::unique_ptr<CanvasSurfaceLayerBridge> m_surfaceLayerBridge;
+
+    mutable RefPtr<Image> m_transparentImage;

[haraken, 2016/07/06 12:46:44]

Why do we need to keep alive the image after copiedImage() returns?

This CL is going to unnecessarily prolong the lifetime of m_transparentImage,
which doesn't seem like a right thing to do to me.

[hajimehoshi, 2016/07/07 10:53:07]

Hmm, I agree.

Do you think it'd make sense if m_transparentImage lives only when m_context is
null?

[haraken, 2016/07/07 11:00:56]

I don't fully understand what problem you're trying to solve.

I don't think HTMLCanvasElement should hold m_transparentImage.
HTMLCanvasElement is just responsible for creating the transparent image and
return the image to someone else. If the someone wants to hold the reference,
the someone should do that.

So the current design looks reasonable to me. HTMLCanvasElement returns a
PassRefPtr to pass the ownership. The receiver is responsible for handling the
ownership. In this particular case, the receiver doesn't need to hold the
reference, so the receiver just drops it immediately. This design doesn't look
strange to me.

 };
 
 } // namespace blink
 
 #endif // HTMLCanvasElement_h