Adding more validation

src/effects/SkDisplacementMapEffect.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 "SkDisplacementMapEffect.h"
 #include "SkFlattenableBuffers.h"
 #include "SkUnPreMultiply.h"
@@ skipping 143 matching lines @@
   , fXChannelSelector(xChannelSelector)
   , fYChannelSelector(yChannelSelector)
   , fScale(scale)
 {
 }
 
 SkDisplacementMapEffect::~SkDisplacementMapEffect() {
 }
 
 SkDisplacementMapEffect::SkDisplacementMapEffect(SkFlattenableReadBuffer& buffer)
-  : INHERITED(buffer)
+  : INHERITED(2, buffer)
 {
     fXChannelSelector = (SkDisplacementMapEffect::ChannelSelectorType) buffer.readInt();
     fYChannelSelector = (SkDisplacementMapEffect::ChannelSelectorType) buffer.readInt();
     fScale            = buffer.readScalar();
     buffer.validate(channel_selector_type_is_valid(fXChannelSelector) &&
                     channel_selector_type_is_valid(fYChannelSelector) &&
                     SkScalarIsFinite(fScale));
 }
 
 void SkDisplacementMapEffect::flatten(SkFlattenableWriteBuffer& buffer) const {
@@ skipping 349 matching lines @@
                                                         const GrGLCaps&) {
     const GrDisplacementMapEffect& displacementMap =
         drawEffect.castEffect<GrDisplacementMapEffect>();
 
     EffectKey xKey = displacementMap.xChannelSelector();
     EffectKey yKey = displacementMap.yChannelSelector() << SkDisplacementMapEffect::kKeyBits;
 
     return xKey | yKey;
 }
 #endif