Forward declare SkStrokeRec in SkPathEffect

Review URL: https://codereview.chromium.org/1312163008
diff --git a/samplecode/ClockFaceView.cpp b/samplecode/ClockFaceView.cpp
index 8362c35..11684e1 100644
--- a/samplecode/ClockFaceView.cpp
+++ b/samplecode/ClockFaceView.cpp
@@ -17,6 +17,7 @@
 #include "SkUtils.h"
 #include "SkColorPriv.h"
 #include "SkColorFilter.h"
+#include "SkStrokeRec.h"
 #include "SkTypeface.h"
 
 static inline SkPMColor rgb2gray(SkPMColor c) {