abstract name of clipping ops, to transtion to a more restricted set

include/core/SkClipOp.h

Index: include/core/SkClipOp.h
diff --git a/include/core/SkClipOp.h b/include/core/SkClipOp.h
new file mode 100644
index 0000000000000000000000000000000000000000..2e4fbbf86806e6f57236a588805af4442d2c3f00
--- /dev/null
+++ b/include/core/SkClipOp.h
@@ -0,0 +1,26 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkClipOp_DEFINED
+#define SkClipOp_DEFINED
+
+#include "SkTypes.h"
+
+// these kept in SkRegion::Op order for now ...
+enum SkClipOp {
+    kDifference_SkClipOp    = 0,
+    kIntersect_SkClipOp     = 1,
+
+    // Goal: remove these, since they can grow the current clip
+
+    kUnion_SkClipOp         = 2,
+    kXOR_SkClipOp           = 3,
+    kReverseDifference_SkClipOp = 4,
+    kReplace_SkClipOp       = 5,
+};
+
+#endif