Make SkAndroidCodec support wbmp

src/codec/SkCodec_wbmp.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.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
@@ skipping 151 matching lines @@
             return y;
         }
         fSwizzler->swizzle(dstRow, fSrcBuffer.get());
         dstRow = SkTAddOffset<void>(dstRow, dstRowBytes);
     }
     return count;
 }
 
 SkCodec::Result SkWbmpCodec::onStartScanlineDecode(const SkImageInfo& dstInfo,
         const Options& options, SkPMColor inputColorTable[], int* inputColorCount) {
-    if (options.fSubset) {

[msarett, 2015/11/13 18:52:44]

You could argue that this goes too far.  Instead, we could disable the
kDivisorMode for AndroidCodec in dm for wbmps.  This is definitely what I'll do
for GIF, where subsets are actually tricky.

However, I think this is fine for wbmp.  If I'm wrong, I'd like to turn this off
again, but I believe that supporting subsets is trivial.

[scroggo, 2015/11/16 14:31:35]

It seems like this doesn't get us any closer to supporting BitmapFactory,
though. Why not focus on that, and then follow up with subset decodes if we
think it's important for wbmp?

[msarett, 2015/11/16 14:46:37]

sgtm

-        // Subsets are not supported.
-        return kUnimplemented;
-    }
-
     if (!valid_alpha(dstInfo.alphaType(), this->getInfo().alphaType())) {
         return kInvalidConversion;
     }
 
     // Fill in the color table
     setup_color_table(dstInfo.colorType(), inputColorTable, inputColorCount);
 
     // Copy the color table to a pointer that can be owned by the scanline decoder
     if (kIndex_8_SkColorType == dstInfo.colorType()) {
         fColorTable.reset(new SkColorTable(inputColorTable, 2));
     }
 
     // Initialize the swizzler
     fSwizzler.reset(this->initializeSwizzler(dstInfo, get_color_ptr(fColorTable.get()), options));
     if (nullptr == fSwizzler.get()) {
         return kInvalidConversion;
     }
 
     fSrcBuffer.reset(fSrcRowBytes);
 
     return kSuccess;
 }