respect srgb gamma when building mips

include/core/SkImageInfo.h

Index: include/core/SkImageInfo.h
diff --git a/include/core/SkImageInfo.h b/include/core/SkImageInfo.h
index 2d89fbf0d6f1102c561600e97279b270bf36f58a..2be04ff5a7a966d7b4e1cb6f94a3b6d0c3a68438 100644
--- a/include/core/SkImageInfo.h
+++ b/include/core/SkImageInfo.h
@@ -285,6 +285,10 @@ public:
         return SkImageInfo(fWidth, fHeight, newColorType, fAlphaType, fProfileType, fColorSpace);
     }
 
+    SkImageInfo makeColorSpace(sk_sp<SkColorSpace> cs) const {
+        return SkImageInfo::Make(fWidth, fHeight, fColorType, fAlphaType, std::move(cs));
+    }
+
     int bytesPerPixel() const { return SkColorTypeBytesPerPixel(fColorType); }
 
     int shiftPerPixel() const { return SkColorTypeShiftPerPixel(fColorType); }