Pass ctm when performing image filtering in GPU backend.

src/gpu/SkGpuDevice.cpp

Index: src/gpu/SkGpuDevice.cpp
diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index 25aacca50941fa068aeb2dabb423a06440ce6495..86c8ba90f8a24c18f14eb20dc03256f341d50aeb 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -939,7 +939,9 @@ void SkGpuDevice::drawPath(const SkDraw& draw, const SkPath& origSrcPath,
                                 grPaint.isAntiAlias(), &mask)) {
                 GrTexture* filtered;
 
-                if (paint.getMaskFilter()->filterMaskGPU(mask.texture(), maskRect, &filtered, true)) {
+                if (paint.getMaskFilter()->filterMaskGPU(mask.texture(),
+                                                         fContext->getMatrix(), maskRect,
+                                                         &filtered, true)) {
                     // filterMaskGPU gives us ownership of a ref to the result
                     SkAutoTUnref<GrTexture> atu(filtered);