introduce Props to surface

src/core/SkSurfacePriv.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkSurfacePriv_DEFINED
+#define SkSurfacePriv_DEFINED
+
+#include "SkSurfaceProps.h"
+
+static inline SkSurfaceProps SkSurfacePropsCopyOrDefault(const SkSurfaceProps* props) {
+    if (props) {
+        return *props;
+    } else {
+        return SkSurfaceProps(SkSurfaceProps::kLegacyFontHost_InitType);
+    }
+}
+
+static inline SkPixelGeometry SkSurfacePropsDefaultPixelGeometry() {
+    return SkSurfaceProps(SkSurfaceProps::kLegacyFontHost_InitType).pixelGeometry();
+}
+
+#endif