Web setting for canvas2d msaa

Source/core/html/HTMLCanvasElement.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 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 479 matching lines @@
         return;
 
     if (deviceSize.width() > MaxSkiaDim || deviceSize.height() > MaxSkiaDim)
         return;
 
     IntSize bufferSize(deviceSize.width(), deviceSize.height());
     if (!bufferSize.width() || !bufferSize.height())
         return;
 
     RenderingMode renderingMode = shouldAccelerate(bufferSize) ? Accelerated : UnacceleratedNonPlatformBuffer;
+    int msaaSampleCount = 0;
+    if (Accelerated == renderingMode && document().settings()->antialiased2dCanvasEnabled())

[Stephen White, 2013/10/18 20:13:12]

Nit: blink style doesn't reverse the == operands (although it doesn't disallow
it either).

[bsalomon, 2013/10/21 13:48:47]

Done, to be more consistent other blink code.

+        msaaSampleCount = document().settings()->accelerated2dCanvasMSAASampleCount();
     OpacityMode opacityMode = !m_context || m_context->hasAlpha() ? NonOpaque : Opaque;
-    m_imageBuffer = ImageBuffer::create(size(), m_deviceScaleFactor, renderingMode, opacityMode);
+    m_imageBuffer = ImageBuffer::create(size(), m_deviceScaleFactor, renderingMode, opacityMode, msaaSampleCount);
     if (!m_imageBuffer)
         return;
     setExternallyAllocatedMemory(4 * width() * height());
     m_imageBuffer->context()->setShouldClampToSourceRect(false);
     m_imageBuffer->context()->setImageInterpolationQuality(DefaultInterpolationQuality);
     if (document().settings() && !document().settings()->antialiased2dCanvasEnabled())
         m_imageBuffer->context()->setShouldAntialias(false);
     // GraphicsContext's defaults don't always agree with the 2d canvas spec.
     // See CanvasRenderingContext2D::State::State() for more information.
     m_imageBuffer->context()->setMiterLimit(10);
@@ skipping 68 matching lines @@
     FloatSize unscaledSize = size();
     FloatSize deviceSize = convertLogicalToDevice(unscaledSize);
     IntSize size(deviceSize.width(), deviceSize.height());
     AffineTransform transform;
     if (size.width() && size.height())
         transform.scaleNonUniform(size.width() / unscaledSize.width(), size.height() / unscaledSize.height());
     return m_imageBuffer->baseTransform() * transform;
 }
 
 }