Consolidate SkCodec functions for handling rewind

src/codec/SkBmpMaskCodec.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 "SkBmpMaskCodec.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 38 matching lines @@
 {}
 
 /*
  * Initiates the bitmap decode
  */
 SkCodec::Result SkBmpMaskCodec::onGetPixels(const SkImageInfo& dstInfo,
                                             void* dst, size_t dstRowBytes,
                                             const Options& opts,
                                             SkPMColor* inputColorPtr,
                                             int* inputColorCount) {
-    if (!this->handleRewind(false)) {
+    if (!this->rewindIfNeeded()) {
         return kCouldNotRewind;
     }
     if (opts.fSubset) {
         // Subsets are not supported.
         return kUnimplemented;
     }
     if (dstInfo.dimensions() != this->getInfo().dimensions()) {
         SkCodecPrintf("Error: scaling not supported.\n");
         return kInvalidScale;
     }
@@ skipping 58 matching lines @@
 
         // Decode the row in destination format
         int row = SkBmpCodec::kBottomUp_RowOrder == this->rowOrder() ? height - 1 - y : y;
         void* dstRow = SkTAddOffset<void>(dst, row * dstRowBytes);
         fMaskSwizzler->swizzle(dstRow, srcRow);
     }
 
     // Finished decoding the entire image
     return kSuccess;
 }