Fix colorType/alphaType checks in SkCodec

src/codec/SkCodec.cpp

Index: src/codec/SkCodec.cpp
diff --git a/src/codec/SkCodec.cpp b/src/codec/SkCodec.cpp
index f5a6d36e3b981a31efba661ba05447f4611c575e..50c172927ee02762f3aaa2a96aceb232966dfdd0 100644
--- a/src/codec/SkCodec.cpp
+++ b/src/codec/SkCodec.cpp
@@ -166,15 +166,6 @@ SkCodec::Result SkCodec::getPixels(const SkImageInfo& info, void* pixels, size_t
         ctable = nullptr;
     }
 
-    {
-        SkAlphaType canonical;
-        if (!SkColorTypeValidateAlphaType(info.colorType(), info.alphaType(), &canonical)

[scroggo, 2016/02/12 17:13:55]

What is this redundant with? I started to remove this recently, but convinced
myself we still wanted it.

[msarett, 2016/02/12 17:41:31]

This just checks that the alphaType matches the colorType.

So we return kInvalidConversion if k565 or kGray is not matched with kOpaque.  I
think that if conversion_possible handles this check, then we don't need it
here.

If we want to handle it here, startScanlineDecode() is missing this check.

[scroggo, 2016/02/12 17:59:00]

Ah, got it. So you're just moving this into a common place where it's called by
startScanlineDecode.

It might be nice to leave it here (and include it for scanline decoding), so
when this gets updated codec gets updated for free. I don't feel strongly about
that though.

-            || canonical != info.alphaType())
-        {
-            return kInvalidConversion;
-        }
-    }
-
     if (!this->rewindIfNeeded()) {
         return kCouldNotRewind;
     }