Include "SkBitmap.h" in CodecAnimTest.cpp

Fixes build
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2449513002

Review-Url: https://codereview.chromium.org/2449513002
diff --git a/tests/CodecAnimTest.cpp b/tests/CodecAnimTest.cpp
index e0a446f..fee6879 100644
--- a/tests/CodecAnimTest.cpp
+++ b/tests/CodecAnimTest.cpp
@@ -5,6 +5,7 @@
  * found in the LICENSE file.
  */
 
+#include "SkBitmap.h"
 #include "SkCodec.h"
 #include "SkStream.h"