Add toString methods to SkImageFilter-derived classes

gm/imagefiltersbase.cpp

Index: gm/imagefiltersbase.cpp
diff --git a/gm/imagefiltersbase.cpp b/gm/imagefiltersbase.cpp
index 749334a61ea28154aa86e27be25895252fb244c7..be8d402528272646b2c5b7cb447e140161517ef8 100644
--- a/gm/imagefiltersbase.cpp
+++ b/gm/imagefiltersbase.cpp
@@ -30,6 +30,7 @@ public:
         return SkNEW(FailImageFilter);
     }
 
+    SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(FailImageFilter)
 
 protected:
@@ -51,6 +52,13 @@ SkFlattenable* FailImageFilter::CreateProc(SkReadBuffer& buffer) {
     return FailImageFilter::Create();
 }
 
+#ifndef SK_IGNORE_TO_STRING
+void FailImageFilter::toString(SkString* str) const {
+    str->appendf("FailImageFilter: (");
+    str->append(")");
+}
+#endif
+
 class IdentityImageFilter : public SkImageFilter {
 public:
     class Registrar {
@@ -65,6 +73,7 @@ public:
         return SkNEW_ARGS(IdentityImageFilter, (input));
     }
 
+    SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(IdentityImageFilter)
 protected:
     IdentityImageFilter(SkImageFilter* input) : INHERITED(1, &input) {}
@@ -87,6 +96,13 @@ SkFlattenable* IdentityImageFilter::CreateProc(SkReadBuffer& buffer) {
     return IdentityImageFilter::Create(common.getInput(0));
 }
 
+#ifndef SK_IGNORE_TO_STRING
+void IdentityImageFilter::toString(SkString* str) const {
+    str->appendf("IdentityImageFilter: (");
+    str->append(")");
+}
+#endif
+
 ///////////////////////////////////////////////////////////////////////////////
 
 static void draw_paint(SkCanvas* canvas, const SkRect& r, SkImageFilter* imf) {