sk_sp: act as if operator bool() not implicit.

Change-Id: Icd426a162ca0c778db7b3373efcb2c546da50273
Reviewed-on: https://skia-review.googlesource.com/22543
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
diff --git a/src/codec/SkGifCodec.cpp b/src/codec/SkGifCodec.cpp
index 7b31a61..df472b9 100644
--- a/src/codec/SkGifCodec.cpp
+++ b/src/codec/SkGifCodec.cpp
@@ -165,7 +165,7 @@
     }
 
     sk_sp<SkColorTable> currColorTable = fReader->getColorTable(colorTableColorType, frameIndex);
-    fCurrColorTableIsReal = currColorTable;
+    fCurrColorTableIsReal = static_cast<bool>(currColorTable);
     if (!fCurrColorTableIsReal) {
         // This is possible for an empty frame. Create a dummy with one value (transparent).
         SkPMColor color = SK_ColorTRANSPARENT;