Fixed bad bitmap size crashes

src/image/SkDataPixelRef.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDataPixelRef.h"
 #include "SkData.h"
 #include "SkFlattenableBuffers.h"
 
 SkDataPixelRef::SkDataPixelRef(SkData* data) : fData(data) {
     fData->ref();
     this->setPreLocked(const_cast<void*>(fData->data()), NULL);
 }
 
 SkDataPixelRef::~SkDataPixelRef() {
     fData->unref();
 }
 
 void* SkDataPixelRef::onLockPixels(SkColorTable** ct) {
     *ct = NULL;
     return const_cast<void*>(fData->data());
 }
 
 void SkDataPixelRef::onUnlockPixels() {
     // nothing to do
 }
 
+size_t SkDataPixelRef::getSize() const {
+    return fData ? fData->size() : 0;
+}
+
 void SkDataPixelRef::flatten(SkFlattenableWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
     buffer.writeDataAsByteArray(fData);
 }
 
 SkDataPixelRef::SkDataPixelRef(SkFlattenableReadBuffer& buffer)
         : INHERITED(buffer, NULL) {
     fData = buffer.readByteArrayAsData();
     this->setPreLocked(const_cast<void*>(fData->data()), NULL);
 }