Add toString methods to SkImageFilter-derived classes

src/effects/SkBlurImageFilter.cpp

 /*
  * Copyright 2011 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkBlurImageFilter.h"
 #include "SkColorPriv.h"
@@ skipping 269 matching lines @@
                                                              true,
                                                              sigma.x(),
                                                              sigma.y()));
     WrapTexture(tex, rect.width(), rect.height(), result);
     return true;
 #else
     SkDEBUGFAIL("Should not call in GPU-less build");
     return false;
 #endif
 }
+
+#ifndef SK_IGNORE_TO_STRING
+void SkBlurImageFilter::toString(SkString* str) const {
+    str->appendf("SkBlurImageFilter: (");
+    str->appendf("sigma: (%f, %f)", fSigma.fWidth, fSigma.fHeight);
+    str->append(")");
+}
+#endif