Improve filtering quality of images downsampled in 2d canvas

Source/core/html/canvas/CanvasRenderingContext2DState.cpp

 // 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.
 
 #include "config.h"
 
 #include "core/html/canvas/CanvasRenderingContext2DState.h"
 
 #include "core/css/CSSFontSelector.h"
 #include "core/html/canvas/CanvasGradient.h"
@@ skipping 386 matching lines @@
 {
     SkXfermode* xferMode = m_strokePaint.getXfermode();
     SkXfermode::Mode mode;
     if (!xferMode || !xferMode->asMode(&mode))
         return SkXfermode::kSrcOver_Mode;
     return mode;
 }
 
 void CanvasRenderingContext2DState::setImageSmoothingEnabled(bool enabled)
 {
-    SkFilterQuality filterQuality = enabled ? kLow_SkFilterQuality : kNone_SkFilterQuality;
+    SkFilterQuality filterQuality = enabled ? kMedium_SkFilterQuality : kNone_SkFilterQuality;
     m_strokePaint.setFilterQuality(filterQuality);
     m_fillPaint.setFilterQuality(filterQuality);
     m_imagePaint.setFilterQuality(filterQuality);
 }
 
 bool CanvasRenderingContext2DState::imageSmoothingEnabled() const
 {
-    return m_imagePaint.getFilterQuality() == kLow_SkFilterQuality;
+    return m_imagePaint.getFilterQuality() == kMedium_SkFilterQuality;
 }
 
 bool CanvasRenderingContext2DState::shouldDrawShadows() const
 {
     return alphaChannel(m_shadowColor) && (m_shadowBlur || !m_shadowOffset.isZero());
 }
 
 const SkPaint* CanvasRenderingContext2DState::getPaint(PaintType paintType, ShadowMode shadowMode, ImageType imageType) const
 {
     SkPaint* paint;
@@ skipping 43 matching lines @@
         paint->setLooper(0);
         paint->setImageFilter(shadowAndForegroundImageFilter());
         return paint;
     }
     paint->setLooper(shadowAndForegroundDrawLooper());
     paint->setImageFilter(0);
     return paint;
 }
 
 } // blink