Add default ctor to SkMask

src/core/SkDraw.cpp

 /*
  * Copyright 2006 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.
  */
 #define __STDC_LIMIT_MACROS
 
 #include "SkDraw.h"
 #include "SkBlitter.h"
@@ skipping 890 matching lines @@
 
 void SkDraw::drawDevMask(const SkMask& srcM, const SkPaint& paint) const {
     if (srcM.fBounds.isEmpty()) {
         return;
     }
 
     const SkMask* mask = &srcM;
 
     SkMask dstM;
     if (paint.getMaskFilter() &&
-            paint.getMaskFilter()->filterMask(&dstM, srcM, *fMatrix, nullptr)) {
+        paint.getMaskFilter()->filterMask(&dstM, srcM, *fMatrix, nullptr)) {
         mask = &dstM;
-    } else {
-        dstM.fImage = nullptr;
     }
     SkAutoMaskFreeImage ami(dstM.fImage);
 
     SkAutoBlitterChoose blitterChooser(fDst, *fMatrix, paint);
     SkBlitter* blitter = blitterChooser.get();
 
     SkAAClipBlitterWrapper wrapper;
     const SkRegion* clipRgn;
 
     if (fRC->isBW()) {
@@ skipping 1081 matching lines @@
     *bounds = devPath.getBounds().makeOutset(SK_ScalarHalf, SK_ScalarHalf).roundOut();
 
     SkIPoint margin = SkIPoint::Make(0, 0);
     if (filter) {
         SkASSERT(filterMatrix);
 
         SkMask srcM, dstM;
 
         srcM.fBounds = *bounds;
         srcM.fFormat = SkMask::kA8_Format;
-        srcM.fImage = nullptr;
         if (!filter->filterMask(&dstM, srcM, *filterMatrix, &margin)) {
             return false;
         }
     }
 
     // (possibly) trim the bounds to reflect the clip
     // (plus whatever slop the filter needs)
     if (clipBounds) {
         // Ugh. Guard against gigantic margins from wacky filters. Without this
         // check we can request arbitrary amounts of slop beyond our visible
@@ skipping 53 matching lines @@
         mask->fImage = SkMask::AllocImage(size);
         memset(mask->fImage, 0, mask->computeImageSize());
     }
 
     if (SkMask::kJustComputeBounds_CreateMode != mode) {
         draw_into_mask(*mask, devPath, style);
     }
 
     return true;
 }