IWYU for some test files starting with 'C'.

Change-Id: Iea274ae52da8b4b87ec55222c856f40a0d88c4e0
Reviewed-on: https://skia-review.googlesource.com/113746
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-on: https://skia-review.googlesource.com/113944
Reviewed-by: Ben Wagner <bungeman@google.com>
diff --git a/tests/ChecksumTest.cpp b/tests/ChecksumTest.cpp
index 1882235..7427187 100644
--- a/tests/ChecksumTest.cpp
+++ b/tests/ChecksumTest.cpp
@@ -8,6 +8,7 @@
 #include "SkChecksum.h"
 #include "SkOpts.h"
 #include "SkRandom.h"
+#include "SkTypes.h"
 #include "Test.h"
 
 DEF_TEST(Checksum, r) {