Make SkAndroidCodec support wbmp

src/codec/SkCodec_wbmp.cpp

Index: src/codec/SkCodec_wbmp.cpp
diff --git a/src/codec/SkCodec_wbmp.cpp b/src/codec/SkCodec_wbmp.cpp
index 900ab6f7017c8781ca82bd2a7707569fd807ce59..5b4c20c1ccd38927a0b7acf2ef995e56518389f2 100644
--- a/src/codec/SkCodec_wbmp.cpp
+++ b/src/codec/SkCodec_wbmp.cpp
@@ -169,11 +169,6 @@ int SkWbmpCodec::onGetScanlines(void* dst, int count, size_t dstRowBytes) {
 
 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;
     }