Destroy SkScanlineDecoder in the SkCodec subclass destructors

tests/CodexTest.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "Resources.h"
 #include "SkBitmap.h"
 #include "SkCodec.h"
@@ skipping 54 matching lines @@
 
     REPORTER_ASSERT(r, result == SkImageGenerator::kSuccess);
     // verify that re-decoding gives the same result.
     md5(bm, &digest2);
     REPORTER_ASSERT(r, digest1 == digest2);
 
     SkScanlineDecoder* scanlineDecoder = codec->getScanlineDecoder(info);
     if (supportsScanlineDecoding) {
         bm.eraseColor(SK_ColorYELLOW);
         REPORTER_ASSERT(r, scanlineDecoder);
+
+        // Regular decodes should be disabled after creating a scanline decoder
+        result = codec->getPixels(info, bm.getPixels(), bm.rowBytes(), NULL, NULL, NULL);
+        REPORTER_ASSERT(r, SkImageGenerator::kInvalidParameters == result);
         for (int y = 0; y < info.height(); y++) {
             result = scanlineDecoder->getScanlines(bm.getAddr(0, y), 1, 0);
             REPORTER_ASSERT(r, result == SkImageGenerator::kSuccess);
         }
         // verify that scanline decoding gives the same result.
         SkMD5::Digest digest3;
         md5(bm, &digest3);
         REPORTER_ASSERT(r, digest3 == digest1);
     } else {
         REPORTER_ASSERT(r, !scanlineDecoder);
@@ skipping 132 matching lines @@
     test_empty(r, "empty_images/zero-embedded.ico");
     test_empty(r, "empty_images/zero-width.bmp");
     test_empty(r, "empty_images/zero-height.bmp");
     test_empty(r, "empty_images/zero-width.jpg");
     test_empty(r, "empty_images/zero-height.jpg");
     test_empty(r, "empty_images/zero-width.png");
     test_empty(r, "empty_images/zero-height.png");
     test_empty(r, "empty_images/zero-width.wbmp");
     test_empty(r, "empty_images/zero-height.wbmp");
 }