Pass ctm when performing image filtering in GPU backend.

src/effects/SkBlurMaskFilter.cpp

Index: src/effects/SkBlurMaskFilter.cpp
diff --git a/src/effects/SkBlurMaskFilter.cpp b/src/effects/SkBlurMaskFilter.cpp
index d2c43d719bcd707ddd58a3adacfe27b6a1015476..f4d032f08fc5c589dcadb3a7a2ebde71968c3301 100644
--- a/src/effects/SkBlurMaskFilter.cpp
+++ b/src/effects/SkBlurMaskFilter.cpp
@@ -38,9 +38,10 @@ public:
                                   const SkMatrix& ctm,
                                   SkRect* maskRect) const SK_OVERRIDE;
     virtual bool filterMaskGPU(GrTexture* src,
+                               const SkMatrix& ctm,
                                const SkRect& maskRect,
                                GrTexture** result,
-                               bool canOverwriteSrc) const;
+                               bool canOverwriteSrc) const SK_OVERRIDE;
 #endif
 
     virtual void computeFastBounds(const SkRect&, SkRect*) const SK_OVERRIDE;
@@ -540,6 +541,7 @@ bool SkBlurMaskFilterImpl::canFilterMaskGPU(const SkRect& srcBounds,
 }
 
 bool SkBlurMaskFilterImpl::filterMaskGPU(GrTexture* src,
+                                         const SkMatrix& matrix,
                                          const SkRect& maskRect,
                                          GrTexture** result,
                                          bool canOverwriteSrc) const {
@@ -549,6 +551,7 @@ bool SkBlurMaskFilterImpl::filterMaskGPU(GrTexture* src,
 
     GrContext::AutoWideOpenIdentityDraw awo(context, NULL);
 
+    // FIXME: This isn't the right matrix.
     SkScalar xformedSigma = this->computeXformedSigma(context->getMatrix());
     SkASSERT(xformedSigma > 0);