Add default ctor to SkMask

tests/BlurTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBlurMask.h"
 #include "SkBlurMaskFilter.h"
 #include "SkBlurDrawLooper.h"
@@ skipping 152 matching lines @@
                             int* result, int resultCount) {
     SkMask src, dst;
 
     src.fBounds.set(0, 0, width, height);
     src.fFormat = SkMask::kA8_Format;
     src.fRowBytes = src.fBounds.width();
     src.fImage = SkMask::AllocImage(src.computeTotalImageSize());
 
     memset(src.fImage, 0xff, src.computeTotalImageSize());
 
-    dst.fImage = nullptr;
-    SkBlurMask::BlurGroundTruth(sigma, &dst, src, kNormal_SkBlurStyle);
+    if (!SkBlurMask::BlurGroundTruth(sigma, &dst, src, kNormal_SkBlurStyle)) {
+        return;
+    }
 
     int midX = dst.fBounds.centerX();
     int midY = dst.fBounds.centerY();
     uint8_t* bytes = dst.getAddr8(midX, midY);
     int i;
     for (i = 0; i < dst.fBounds.width()-(midX-dst.fBounds.fLeft); ++i) {
         if (i < resultCount) {
             result[i] = bytes[i];
         }
     }
@@ skipping 366 matching lines @@
             if (mf.get()) {
                 SkMaskFilter::BlurRec rec;
                 bool success = mf->asABlur(&rec);
                 REPORTER_ASSERT(reporter, !success);
             }
         }
     }
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////