use possible corrected info when creating pixelref

TBR=halcanary, scroggo

Author: reed@google.com

Review URL: https://codereview.chromium.org/518103002
diff --git a/src/lazy/SkDiscardablePixelRef.cpp b/src/lazy/SkDiscardablePixelRef.cpp
index ce38a4a..a86c3de 100644
--- a/src/lazy/SkDiscardablePixelRef.cpp
+++ b/src/lazy/SkDiscardablePixelRef.cpp
@@ -105,7 +105,10 @@
         || (!dst->setInfo(info))) {
         return false;
     }
-    SkASSERT(dst->colorType() != kUnknown_SkColorType);
+    // Since dst->setInfo() may have changed/fixed-up info, we copy it back from that bitmap
+    info = dst->info();
+
+    SkASSERT(info.colorType() != kUnknown_SkColorType);
     if (dst->empty()) {  // Use a normal pixelref.
         return dst->allocPixels();
     }