Test scaling for small images

include/codec/SkCodec.h

Index: include/codec/SkCodec.h
diff --git a/include/codec/SkCodec.h b/include/codec/SkCodec.h
index 3465c1df5bc1df588e728dafd2622bbd097e6cd8..ae9524b8b78b539cfcf7b2815c2d9c63e0e57944 100644
--- a/include/codec/SkCodec.h
+++ b/include/codec/SkCodec.h
@@ -55,6 +55,17 @@ public:
      *  scale that it can natively support
      */
     SkISize getScaledDimensions(float desiredScale) const {
+        // Negative and zero scales are errors.
+        SkASSERT(desiredScale > 0.0f);
+        if (desiredScale <= 0.0f) {
+            return SkISize::Make(0, 0);
+        }
+
+        // Upscaling is not supported. Return the original size if the client
+        // requests an upscale.
+        if (desiredScale >= 1.0f) {
+            return this->getInfo().dimensions();
+        }
         return this->onGetScaledDimensions(desiredScale);
     }