Consolidate SkCodec functions for handling rewind

src/codec/SkBmpCodec.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 "SkBmpMaskCodec.h"
 #include "SkBmpRLECodec.h"
@@ skipping 515 matching lines @@
     return NULL;
 }
 
 SkBmpCodec::SkBmpCodec(const SkImageInfo& info, SkStream* stream,
         uint16_t bitsPerPixel, RowOrder rowOrder)
     : INHERITED(info, stream)
     , fBitsPerPixel(bitsPerPixel)
     , fRowOrder(rowOrder)
 {}
 
-/*
- * Rewinds the image stream if necessary
- */
-bool SkBmpCodec::handleRewind(bool inIco) {
-    SkCodec::RewindState rewindState = this->rewindIfNeeded();
-    if (rewindState == kCouldNotRewind_RewindState) {
-        return false;
-    } else if (rewindState == kRewound_RewindState) {
-        if (!SkBmpCodec::ReadHeader(this->stream(), inIco, NULL)) {
-            return false;
-        }
-    }
-    return true;
+bool SkBmpCodec::onRewind() {
+    return SkBmpCodec::ReadHeader(this->stream(), this->inIco(), NULL);
 }
 
 /*
  * Get the destination row to start filling from
  * Used to fill the remainder of the image on incomplete input for bmps
  * This is tricky since bmps may be kTopDown or kBottomUp.  For kTopDown,
  * we start filling from where we left off, but for kBottomUp we start
  * filling at the top of the image.
  */
 void* SkBmpCodec::getDstStartRow(void* dst, size_t dstRowBytes, int32_t y) const {
     return (kTopDown_RowOrder == fRowOrder) ? SkTAddOffset<void*>(dst, y * dstRowBytes) : dst;
 }
 
 /*
  * Compute the number of colors in the color table
  */
 uint32_t SkBmpCodec::computeNumColors(uint32_t numColors) {
     // Zero is a default for maxColors
     // Also set fNumColors to maxColors when it is too large
     uint32_t maxColors = 1 << fBitsPerPixel;
     if (numColors == 0 || numColors >= maxColors) {
         return maxColors;
     }
     return numColors;
 }