Make SkPath fFirstDirection atomic to fix tsan.

include/core/SkPath.h

Index: include/core/SkPath.h
diff --git a/include/core/SkPath.h b/include/core/SkPath.h
index caf4cfe5ecc9aa0e4e189c96153ea3c8d0f4ff54..d3673b6d5d35504aff815f9dcb58b06582545a69 100644
--- a/include/core/SkPath.h
+++ b/include/core/SkPath.h
@@ -938,13 +938,13 @@ private:
         kCurrent_Version = 1
     };
 
-    SkAutoTUnref<SkPathRef> fPathRef;
+    SkAutoTUnref<SkPathRef>   fPathRef;
 
-    int                 fLastMoveToIndex;
-    uint8_t             fFillType;
-    mutable uint8_t     fConvexity;
-    mutable uint8_t     fFirstDirection;    // SkPathPriv::FirstDirection
-    mutable SkBool8     fIsVolatile;
+    int                       fLastMoveToIndex;
+    uint8_t                   fFillType;
+    mutable uint8_t           fConvexity;
+    mutable SkAtomic<uint8_t> fFirstDirection;    // SkPathPriv::FirstDirection
+    mutable SkBool8           fIsVolatile;
 
     /** Resets all fields other than fPathRef to their initial 'empty' values.
      *  Assumes the caller has already emptied fPathRef.