Implement support for a Context parameter in image filters

src/effects/SkRectShaderImageFilter.cpp

Index: src/effects/SkRectShaderImageFilter.cpp
diff --git a/src/effects/SkRectShaderImageFilter.cpp b/src/effects/SkRectShaderImageFilter.cpp
index 27b39d7fb1dde27fb3926738b5df9edd570af91c..dad0e02525ea913ed29f568e989b17fbf2e1e319 100644
--- a/src/effects/SkRectShaderImageFilter.cpp
+++ b/src/effects/SkRectShaderImageFilter.cpp
@@ -52,12 +52,12 @@ SkRectShaderImageFilter::~SkRectShaderImageFilter() {
 
 bool SkRectShaderImageFilter::onFilterImage(Proxy* proxy,
                                             const SkBitmap& source,
-                                            const SkMatrix& ctm,
+                                            const Context& ctx,
                                             SkBitmap* result,
                                             SkIPoint* offset) const {
     SkIRect bounds;
     source.getBounds(&bounds);
-    if (!this->applyCropRect(&bounds, ctm)) {
+    if (!this->applyCropRect(&bounds, ctx.ctm())) {
         return false;
     }
 
@@ -69,7 +69,7 @@ bool SkRectShaderImageFilter::onFilterImage(Proxy* proxy,
     SkCanvas canvas(device.get());
     SkPaint paint;
     paint.setShader(fShader);
-    SkMatrix matrix(ctm);
+    SkMatrix matrix(ctx.ctm());
     matrix.postTranslate(SkIntToScalar(-bounds.left()), SkIntToScalar(-bounds.top()));
     fShader->setLocalMatrix(matrix);
     SkRect rect = SkRect::MakeWH(SkIntToScalar(bounds.width()), SkIntToScalar(bounds.height()));