Implement SkAshmemDiscardableMemory

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"
 
@@ skipping 13 matching lines @@
 
 SkDiscardablePixelRef::~SkDiscardablePixelRef() {
     SkDELETE(fGenerator);
 }
 
 void* SkDiscardablePixelRef::onLockPixels(SkColorTable**) {
     if (fDiscardableMemory != NULL) {
         if (fDiscardableMemory->lock()) {
             return fDiscardableMemory->data();
         }
+        SkDELETE(fDiscardableMemory);
         fDiscardableMemory = NULL;
     }
     fDiscardableMemory = SkDiscardableMemory::Create(fSize);
     if (NULL == fDiscardableMemory) {
         return NULL;  // Memory allocation failed.
     }
     void* pixels = fDiscardableMemory->data();
     if (!fGenerator->getPixels(fInfo, pixels, fRowBytes)) {
         return NULL;  // TODO(halcanary) Find out correct thing to do.
     }
@@ skipping 15 matching lines @@
         SkDELETE(generator);
         return false;
     }
     SkAutoTUnref<SkDiscardablePixelRef> ref(SkNEW_ARGS(SkDiscardablePixelRef,
                                                    (generator, info,
                                                     dst->getSize(),
                                                     dst->rowBytes())));
     dst->setPixelRef(ref);
     return true;
 }