Add toString methods to SkImageFilter-derived classes

tests/ImageFilterTest.cpp

Index: tests/ImageFilterTest.cpp
diff --git a/tests/ImageFilterTest.cpp b/tests/ImageFilterTest.cpp
index 9fd4351b42a65c9cc575183d66b71017fac1200a..b67383682bf77b70ad7fb8598ae42dc3689a68e5 100644
--- a/tests/ImageFilterTest.cpp
+++ b/tests/ImageFilterTest.cpp
@@ -55,6 +55,7 @@ public:
         return true;
     }
 
+    SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(MatrixTestImageFilter)
 
 protected:
@@ -81,6 +82,13 @@ SkFlattenable* MatrixTestImageFilter::CreateProc(SkReadBuffer& buffer) {
     return SkNEW_ARGS(MatrixTestImageFilter, (reporter, matrix));
 }
 
+#ifndef SK_IGNORE_TO_STRING
+void MatrixTestImageFilter::toString(SkString* str) const {
+    str->appendf("MatrixTestImageFilter: (");
+    str->append(")");
+}
+#endif
+
 static void make_small_bitmap(SkBitmap& bitmap) {
     bitmap.allocN32Pixels(kBitmapSize, kBitmapSize);
     SkCanvas canvas(bitmap);