Consolidate SkCodec functions for handling rewind

src/codec/SkCodec.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 "SkBmpCodec.h"
 #include "SkCodec.h"
 #include "SkData.h"
@@ skipping 65 matching lines @@
 }
 
 SkCodec::SkCodec(const SkImageInfo& info, SkStream* stream)
     : fInfo(info)
     , fStream(stream)
     , fNeedsRewind(false)
 {}
 
 SkCodec::~SkCodec() {}
 
-SkCodec::RewindState SkCodec::rewindIfNeeded() {
+bool SkCodec::rewindIfNeeded() {
     // Store the value of fNeedsRewind so we can update it. Next read will
     // require a rewind.
     const bool needsRewind = fNeedsRewind;
     fNeedsRewind = true;
     if (!needsRewind) {
-        return kNoRewindNecessary_RewindState;
+        return true;
     }
-    return fStream->rewind() ? kRewound_RewindState
-                             : kCouldNotRewind_RewindState;
+
+    if (!fStream->rewind()) {
+        return false;
+    }
+
+    return this->onRewind();
 }
 
 SkCodec::Result SkCodec::getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
                                    const Options* options, SkPMColor ctable[], int* ctableCount) {
     if (kUnknown_SkColorType == info.colorType()) {
         return kInvalidConversion;
     }
     if (NULL == pixels) {
         return kInvalidParameters;
     }
@@ skipping 22 matching lines @@
 
     if ((kIncompleteInput == result || kSuccess == result) && ctableCount) {
         SkASSERT(*ctableCount >= 0 && *ctableCount <= 256);
     }
     return result;
 }
 
 SkCodec::Result SkCodec::getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes) {
     return this->getPixels(info, pixels, rowBytes, NULL, NULL, NULL);
 }