Add toString methods to SkImageFilter-derived classes

src/effects/SkMagnifierImageFilter.cpp

Index: src/effects/SkMagnifierImageFilter.cpp
diff --git a/src/effects/SkMagnifierImageFilter.cpp b/src/effects/SkMagnifierImageFilter.cpp
index ae6637b28227f12b7b09fa4500b310737b7ff598..e236da53ffb126af00be7b6db30b1ed7f9a405e3 100644
--- a/src/effects/SkMagnifierImageFilter.cpp
+++ b/src/effects/SkMagnifierImageFilter.cpp
@@ -357,3 +357,13 @@ bool SkMagnifierImageFilter::onFilterImage(Proxy*, const SkBitmap& src,
     }
     return true;
 }
+
+#ifndef SK_IGNORE_TO_STRING
+void SkMagnifierImageFilter::toString(SkString* str) const {
+    str->appendf("SkMagnifierImageFilter: (");
+    str->appendf("src: (%f,%f,%f,%f) ",
+                 fSrcRect.fLeft, fSrcRect.fTop, fSrcRect.fRight, fSrcRect.fBottom);
+    str->appendf("inset: %f", fInset);
+    str->append(")");
+}
+#endif