SkCodec: add wbmp class

src/codec/SkCodec_libpng.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 "SkCodec_libpng.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 402 matching lines @@
     // FIXME: Here is where we should likely insert some of the modifications
     // made in the factory.
     png_read_update_info(fPng_ptr, fInfo_ptr);
 
     return kSuccess;
 }
 
 SkCodec::Result SkPngCodec::onGetPixels(const SkImageInfo& requestedInfo, void* dst,
                                         size_t rowBytes, const Options& options,
                                         SkPMColor ctable[], int* ctableCount) {
-    if (!this->rewindIfNeeded()) {
+    SkCodec::RewindState rewindState = this->rewindIfNeeded();
+    if (rewindState == kCouldNotRewind_RewindState) {
+        return kCouldNotRewind;
+    } else if (rewindState == kRewound_RewindState) {
+        // TODO(scroggo):  handle rewinds
         return kCouldNotRewind;
     }
     if (requestedInfo.dimensions() != this->getInfo().dimensions()) {
         return kInvalidScale;
     }
     if (!conversion_possible(requestedInfo, this->getInfo())) {
         return kInvalidConversion;
     }
 
     const Result result = this->initializeSwizzler(requestedInfo, dst, rowBytes,
@@ skipping 138 matching lines @@
 
     SkASSERT(fNumberPasses != INVALID_NUMBER_PASSES);
     if (fNumberPasses > 1) {
         // We cannot efficiently do scanline decoding.
         return NULL;
     }
 
     return SkNEW_ARGS(SkPngScanlineDecoder, (dstInfo, this));
 }