IWYU for gms.

This almost gets gms to be iwyu clean. The last bit is around gm.cpp
and the tracing framework and its use of atomic. Will also need a way
of keeping things from regressing, which is difficult due to needing to
do this outside-in.

Change-Id: I1393531e99da8b0f1a29f55c53c86d53f459af7d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/211593
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
diff --git a/gm/hugepath.cpp b/gm/hugepath.cpp
index 157111f..0d2902a 100644
--- a/gm/hugepath.cpp
+++ b/gm/hugepath.cpp
@@ -7,7 +7,10 @@
 
 #include "gm/gm.h"
 #include "include/core/SkCanvas.h"
+#include "include/core/SkPaint.h"
 #include "include/core/SkPath.h"
+#include "include/core/SkRect.h"
+#include "include/core/SkRefCnt.h"
 #include "include/core/SkSurface.h"
 
 DEF_SIMPLE_GM(path_huge_crbug_800804, canvas, 50, 600) {