Refactoring ImageBuffer to decouple it from Canvas2DLayerBridge

Source/core/rendering/svg/RenderSVGResourcePattern.cpp

Index: Source/core/rendering/svg/RenderSVGResourcePattern.cpp
diff --git a/Source/core/rendering/svg/RenderSVGResourcePattern.cpp b/Source/core/rendering/svg/RenderSVGResourcePattern.cpp
index 49a587f962732fe0ef6cd4e4d4e0371949d2615d..2e3bf561ca74a4ad989f0def529656c0297064bd 100644
--- a/Source/core/rendering/svg/RenderSVGResourcePattern.cpp
+++ b/Source/core/rendering/svg/RenderSVGResourcePattern.cpp
@@ -26,6 +26,7 @@
 #include "core/rendering/svg/SVGRenderSupport.h"
 #include "core/rendering/svg/SVGRenderingContext.h"
 #include "core/svg/SVGFitToViewBox.h"
+#include "platform/graphics/UnacceleratedImageBufferSurface.h"
 
 namespace WebCore {
 
@@ -240,12 +241,18 @@ PassOwnPtr<ImageBuffer> RenderSVGResourcePattern::createTileImage(const PatternA
 {
     clampedAbsoluteTileBoundaries = SVGRenderingContext::clampedAbsoluteTargetRect(absoluteTileBoundaries);
 
-    OwnPtr<ImageBuffer> tileImage = ImageBuffer::createBufferForTile(absoluteTileBoundaries.size(), clampedAbsoluteTileBoundaries.size(), Unaccelerated);
-    if (!tileImage)
+    IntSize imageSize(roundedIntSize(clampedAbsoluteTileBoundaries.size()));
+    if (imageSize.isEmpty())
+        return nullptr;
+    OwnPtr<ImageBufferSurface> surface = adoptPtr(new UnacceleratedImageBufferSurface(imageSize));
+    if (!surface->isValid())
         return nullptr;
+    OwnPtr<ImageBuffer> tileImage = adoptPtr(new ImageBuffer(surface.release()));
 
     GraphicsContext* tileImageContext = tileImage->context();
     ASSERT(tileImageContext);
+    IntSize unclampedImageSize(roundedIntSize(absoluteTileBoundaries.size()));
+    tileImageContext->scale(FloatSize(unclampedImageSize.width() / absoluteTileBoundaries.width(), unclampedImageSize.height() / absoluteTileBoundaries.height()));
 
     // The image buffer represents the final rendered size, so the content has to be scaled (to avoid pixelation).
     tileImageContext->scale(FloatSize(clampedAbsoluteTileBoundaries.width() / tileBoundaries.width(),