Implement image-rendering:pixelated for accelerated 2D canvases.

Source/core/html/HTMLCanvasElement.cpp

Index: Source/core/html/HTMLCanvasElement.cpp
diff --git a/Source/core/html/HTMLCanvasElement.cpp b/Source/core/html/HTMLCanvasElement.cpp
index 398e2314071092d48ecda73f84c3e49c5c430842..4d1fbe8b59ad6f92203fd9cf843cdc98408353f1 100644
--- a/Source/core/html/HTMLCanvasElement.cpp
+++ b/Source/core/html/HTMLCanvasElement.cpp
@@ -102,6 +102,7 @@ inline HTMLCanvasElement::HTMLCanvasElement(Document& document)
     , m_didFailToCreateImageBuffer(false)
     , m_imageBufferIsClear(false)
 {
+    setHasCustomStyleCallbacks();
 }
 
 DEFINE_NODE_FACTORY(HTMLCanvasElement)
@@ -134,6 +135,13 @@ RenderObject* HTMLCanvasElement::createRenderer(RenderStyle* style)
     return HTMLElement::createRenderer(style);
 }
 
+void HTMLCanvasElement::didRecalcStyle(StyleRecalcChange)
+{
+    if (!hasImageBuffer())
+        return;
+    m_imageBuffer->setFilterLevel(computedStyle()->imageRendering() == ImageRenderingPixelated ? SkPaint::kNone_FilterLevel : SkPaint::kLow_FilterLevel);
+}
+
 Node::InsertionNotificationRequest HTMLCanvasElement::insertedInto(ContainerNode* node)
 {
     setIsInCanvasSubtree(true);
@@ -577,6 +585,7 @@ void HTMLCanvasElement::createImageBufferInternal()
 
     m_imageBuffer = ImageBuffer::create(surface.release());
     m_imageBuffer->setClient(this);
+    m_imageBuffer->setFilterLevel(computedStyle()->imageRendering() == ImageRenderingPixelated ? SkPaint::kNone_FilterLevel : SkPaint::kLow_FilterLevel);
 
     m_didFailToCreateImageBuffer = false;
 
@@ -590,7 +599,7 @@ void HTMLCanvasElement::createImageBufferInternal()
     m_imageBuffer->setClient(this);
     m_imageBuffer->context()->setShouldClampToSourceRect(false);
     m_imageBuffer->context()->disableAntialiasingOptimizationForHairlineImages();
-    m_imageBuffer->context()->setImageInterpolationQuality(CanvasDefaultInterpolationQuality);
+    m_imageBuffer->context()->setImageInterpolationQuality(computedStyle()->imageRendering() == ImageRenderingOptimizeContrast ? InterpolationLow : CanvasDefaultInterpolationQuality);
     // Enabling MSAA overrides a request to disable antialiasing. This is true regardless of whether the
     // rendering mode is accelerated or not. For consistency, we don't want to apply AA in accelerated
     // canvases but not in unaccelerated canvases.
@@ -749,6 +758,8 @@ PassRefPtr<Image> HTMLCanvasElement::getSourceImageForCanvas(SourceImageMode mod
         return nullptr;
     }
 
+    m_imageBuffer->willAccessPixels();
+
     if (m_context && m_context->is3d()) {
         m_context->paintRenderingResultsToCanvas(BackBuffer);
         *status = ExternalSourceImageStatus;