Fill incomplete images in SkCodec parent class

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 139 matching lines @@
     stream.reset(resource(path));
     SkAutoTDelete<SkScanlineDecoder> scanlineDecoder(
             SkScanlineDecoder::NewFromStream(stream.detach()));
     if (supportsScanlineDecoding) {
         bm.eraseColor(SK_ColorYELLOW);
         REPORTER_ASSERT(r, scanlineDecoder);
 
         REPORTER_ASSERT(r, scanlineDecoder->start(info) == SkCodec::kSuccess);
 
         for (int y = 0; y < info.height(); y++) {
-            result = scanlineDecoder->getScanlines(bm.getAddr(0, y), 1, 0);
-            REPORTER_ASSERT(r, result == SkCodec::kSuccess);
+            const uint32_t lines = scanlineDecoder->getScanlines(bm.getAddr(0, y), 1, 0);
+            REPORTER_ASSERT(r, 1 == lines);
         }
         // verify that scanline decoding gives the same result.
         if (SkScanlineDecoder::kTopDown_SkScanlineOrder == scanlineDecoder->getScanlineOrder()) {
             compare_to_good_digest(r, digest, bm);
         }
     } else {
         REPORTER_ASSERT(r, !scanlineDecoder);
     }
 
     // The rest of this function tests decoding subsets, and will decode an arbitrary number of
@@ skipping 218 matching lines @@
     REPORTER_ASSERT(r, SkCodec::kInvalidParameters == result);
     result = decoder->start(
         decoder->getInfo().makeColorType(kIndex_8_SkColorType));
     REPORTER_ASSERT(r, SkCodec::kInvalidParameters == result);
 }
 
 DEF_TEST(Codec_Params, r) {
     test_invalid_parameters(r, "index8.png");
     test_invalid_parameters(r, "mandrill.wbmp");
 }