Add toString methods to SkImageFilter-derived classes

src/effects/SkTestImageFilters.cpp

 
 #include "SkTestImageFilters.h"
 #include "SkCanvas.h"
 #include "SkDevice.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 
 // Simple helper canvas that "takes ownership" of the provided device, so that
 // when this canvas goes out of scope, so will its device. Could be replaced
 // with the following:
@@ skipping 62 matching lines @@
 
 SkFlattenable* SkDownSampleImageFilter::CreateProc(SkReadBuffer& buffer) {
     SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);
     return Create(buffer.readScalar(), common.getInput(0));
 }
 
 void SkDownSampleImageFilter::flatten(SkWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
     buffer.writeScalar(fScale);
 }
+
+#ifndef SK_IGNORE_TO_STRING
+void SkDownSampleImageFilter::toString(SkString* str) const {
+    str->appendf("SkDownSampleImageFilter: (");
+    str->append(")");
+}
+#endif