Make header files self-sufficient

Change-Id: Ice7d761b1023da77e50e5d6aa597964f7d9aa1d8
Reviewed-on: https://skia-review.googlesource.com/8302
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Mike Reed <reed@google.com>
diff --git a/tests/PathOpsThreadedCommon.h b/tests/PathOpsThreadedCommon.h
index 6cc0c3f4..1462aa2 100644
--- a/tests/PathOpsThreadedCommon.h
+++ b/tests/PathOpsThreadedCommon.h
@@ -7,8 +7,10 @@
 #ifndef PathOpsThreadedCommon_DEFINED
 #define PathOpsThreadedCommon_DEFINED
 
+#include "SkBitmap.h"
 #include "SkGraphics.h"
 #include "SkPath.h"
+#include "SkPathOps.h"
 #include "SkString.h"
 #include "SkTDArray.h"