Report "correct" color type for lazy images

This may just be a suggested color type, but it's better than nothing.
In conjunction with a codec change, this would make it possible to
detect 8 vs. 16-bit PNG, for example.

Bug: skia:
Change-Id: I0886cca004b10ac9707c66e816316cf6f822ab01
Reviewed-on: https://skia-review.googlesource.com/156640
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

src/image/SkImage_Lazy.h

@@ -38,7 +38,7 @@ public:
         return fInfo;
     }
     SkColorType onColorType() const override {
-        return kUnknown_SkColorType;
+        return fInfo.colorType();
     }
     SkAlphaType onAlphaType() const override {
         return fInfo.alphaType();