Option for SkCodec to treat dst as all zeroes.

src/lazy/SkDiscardablePixelRef.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 "SkDiscardablePixelRef.h"
 #include "SkDiscardableMemory.h"
 #include "SkImageGenerator.h"
@@ skipping 53 matching lines @@
     if (NULL == fDiscardableMemory) {
         fDiscardableMemoryIsLocked = false;
         return false;  // Memory allocation failed.
     }
 
     void* pixels = fDiscardableMemory->data();
     const SkImageInfo& info = this->info();
     SkPMColor colors[256];
     int colorCount = 0;
 
-    const SkImageGenerator::Result result = fGenerator->getPixels(info, pixels, fRowBytes,
+    const SkImageGenerator::Result result = fGenerator->getPixels(info, pixels, fRowBytes, NULL,
                                                                   colors, &colorCount);
     switch (result) {
         case SkImageGenerator::kSuccess:
         case SkImageGenerator::kIncompleteInput:
             break;
         default:
             fDiscardableMemory->unlock();
             fDiscardableMemoryIsLocked = false;
             SkDELETE(fDiscardableMemory);
             fDiscardableMemory = NULL;
@@ skipping 49 matching lines @@
 // These are the public API
 
 bool SkInstallDiscardablePixelRef(SkImageGenerator* generator, SkBitmap* dst) {
     return SkInstallDiscardablePixelRef(generator, dst, NULL);
 }
 
 bool SkInstallDiscardablePixelRef(SkData* encoded, SkBitmap* dst) {
     SkImageGenerator* generator = SkImageGenerator::NewFromData(encoded);
     return generator ? SkInstallDiscardablePixelRef(generator, dst, NULL) : false;
 }