Add toString methods to SkImageFilter-derived classes

src/effects/SkMatrixConvolutionImageFilter.cpp

Index: src/effects/SkMatrixConvolutionImageFilter.cpp
diff --git a/src/effects/SkMatrixConvolutionImageFilter.cpp b/src/effects/SkMatrixConvolutionImageFilter.cpp
index 045f6a96d58cce817489badad9c3162e01c342b6..e9dd87852f4ee406d0165e65ee7b2cd354d69bd3 100644
--- a/src/effects/SkMatrixConvolutionImageFilter.cpp
+++ b/src/effects/SkMatrixConvolutionImageFilter.cpp
@@ -369,3 +369,20 @@ bool SkMatrixConvolutionImageFilter::asFragmentProcessor(GrFragmentProcessor** f
     return true;
 }
 #endif
+
+#ifndef SK_IGNORE_TO_STRING
+void SkMatrixConvolutionImageFilter::toString(SkString* str) const {
+    str->appendf("SkMatrixConvolutionImageFilter: (");
+    str->appendf("size: (%d,%d) kernel: (", fKernelSize.width(), fKernelSize.height());
+    for (int y = 0; y < fKernelSize.height(); y++) {
+        for (int x = 0; x < fKernelSize.width(); x++) {
+            str->appendf("%f ", fKernel[y * fKernelSize.width() + x]);
+        }
+    }
+    str->appendf(")");
+    str->appendf("gain: %f bias: %f ", fGain, fBias);
+    str->appendf("offset: (%d, %d) ", fKernelOffset.fX, fKernelOffset.fY);
+    str->appendf("convolveAlpha: %s", fConvolveAlpha ? "true" : "false");
+    str->append(")");
+}
+#endif