Fix bug in SkGifCodec / Switch SkImageDec tests to use Codec

tests/FrontBufferedStreamTest.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 "SkBitmap.h"
+#include "SkCodec.h"
 #include "SkFrontBufferedStream.h"
-#include "SkImageDecoder.h"
 #include "SkRefCnt.h"
 #include "SkStream.h"
 #include "SkTypes.h"
 #include "Test.h"
 
 static void test_read(skiatest::Reporter* reporter, SkStream* bufferedStream,
                       const void* expectations, size_t bytesToRead) {
     // output for reading bufferedStream.
     SkAutoMalloc storage(bytesToRead);
 
@@ skipping 261 matching lines @@
         return fReadAfterEnd;
     }
 private:
     bool fAtEnd;
     bool fReadAfterEnd;
 };
 
 DEF_TEST(ShortFrontBufferedStream, reporter) {
     FailingStream* failingStream = new FailingStream;
     SkAutoTDelete<SkStreamRewindable> stream(SkFrontBufferedStream::Create(failingStream, 64));
-    SkBitmap bm;
-    // The return value of DecodeStream is not important. We are just using DecodeStream because
-    // it simulates a bug. DecodeStream will read the stream, then rewind, then attempt to read
-    // again. FrontBufferedStream::read should not continue to read its underlying stream beyond
-    // its end.
-    SkImageDecoder::DecodeStream(stream, &bm);
+
+    // This will fail to create a codec.  However, what we really want to test is that we
+    // won't read past the end of the stream.
+    SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(stream.detach()));
     REPORTER_ASSERT(reporter, !failingStream->readAfterEnd());
 }