Initial error handling code

src/effects/SkDropShadowImageFilter.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDropShadowImageFilter.h"
 
 #include "SkBitmap.h"
@@ skipping 11 matching lines @@
     , fColor(color)
 {
 }
 
 SkDropShadowImageFilter::SkDropShadowImageFilter(SkFlattenableReadBuffer& buffer) : INHERITED(buffer)
 {
     fDx = buffer.readScalar();
     fDy = buffer.readScalar();
     fSigma = buffer.readScalar();
     fColor = buffer.readColor();
+    buffer.validate(SkScalarIsFinite(fDx) &&
+                    SkScalarIsFinite(fDy) &&
+                    SkScalarIsFinite(fSigma));
 }
 
 void SkDropShadowImageFilter::flatten(SkFlattenableWriteBuffer& buffer) const
 {
     this->INHERITED::flatten(buffer);
     buffer.writeScalar(fDx);
     buffer.writeScalar(fDy);
     buffer.writeScalar(fSigma);
     buffer.writeColor(fColor);
 }
@@ skipping 11 matching lines @@
     SkAutoTUnref<SkColorFilter> colorFilter(SkColorFilter::CreateModeFilter(fColor, SkXfermode::kSrcIn_Mode));
     SkPaint paint;
     paint.setImageFilter(blurFilter.get());
     paint.setColorFilter(colorFilter.get());
     paint.setXfermodeMode(SkXfermode::kSrcOver_Mode);
     canvas.drawBitmap(src, fDx, fDy, &paint);
     canvas.drawBitmap(src, 0, 0);
     *result = device->accessBitmap(false);
     return true;
 }