Implement onSkipScanlines() for bmp and wbmp

src/codec/SkBmpStandardCodec.cpp

Index: src/codec/SkBmpStandardCodec.cpp
diff --git a/src/codec/SkBmpStandardCodec.cpp b/src/codec/SkBmpStandardCodec.cpp
index 66a8c9a12a12c4d1af73c3ebd7d83856a55b9ac8..47b10701d332156a63ece8f08f852f3d09dc443f 100644
--- a/src/codec/SkBmpStandardCodec.cpp
+++ b/src/codec/SkBmpStandardCodec.cpp
@@ -25,8 +25,7 @@ SkBmpStandardCodec::SkBmpStandardCodec(const SkImageInfo& info, SkStream* stream
     , fBytesPerColor(bytesPerColor)
     , fOffset(offset)
     , fSwizzler(nullptr)
-    , fSrcRowBytes(SkAlign4(compute_row_bytes(this->getInfo().width(), this->bitsPerPixel())))
-    , fSrcBuffer(new uint8_t [fSrcRowBytes])
+    , fSrcBuffer(new uint8_t [this->srcRowBytes()])
     , fIsOpaque(isOpaque)
     , fInIco(inIco)
     , fAndMaskRowBytes(fInIco ? SkAlign4(compute_row_bytes(this->getInfo().width(), 1)) : 0)
@@ -225,7 +224,7 @@ int SkBmpStandardCodec::decodeRows(const SkImageInfo& dstInfo, void* dst, size_t
     const int height = dstInfo.height();
     for (int y = 0; y < height; y++) {
         // Read a row of the input
-        if (this->stream()->read(fSrcBuffer.get(), fSrcRowBytes) != fSrcRowBytes) {
+        if (this->stream()->read(fSrcBuffer.get(), this->srcRowBytes()) != this->srcRowBytes()) {
             SkCodecPrintf("Warning: incomplete input stream.\n");
             return y;
         }
@@ -262,7 +261,7 @@ int SkBmpStandardCodec::decodeRows(const SkImageInfo& dstInfo, void* dst, size_t
 
         // Calculate how many bytes we must skip to reach the AND mask.
         const int remainingScanlines = this->getInfo().height() - startScanline - height;
-        const size_t bytesToSkip = remainingScanlines * fSrcRowBytes +
+        const size_t bytesToSkip = remainingScanlines * this->srcRowBytes() +
                 startScanline * fAndMaskRowBytes;
         const size_t subStreamStartPosition = currPosition + bytesToSkip;
         if (subStreamStartPosition >= length) {