Add '... implement SVGUnitTypes' to a bunch of SVG*Elements

third_party/WebKit/Source/core/svg/SVGMaskElement.h

Index: third_party/WebKit/Source/core/svg/SVGMaskElement.h
diff --git a/third_party/WebKit/Source/core/svg/SVGMaskElement.h b/third_party/WebKit/Source/core/svg/SVGMaskElement.h
index e3f7c2b877b9be8d4c1ca51f374dcc258fe16a00..d66d853d42eacd668943a1a4bdf1b1d985e496f8 100644
--- a/third_party/WebKit/Source/core/svg/SVGMaskElement.h
+++ b/third_party/WebKit/Source/core/svg/SVGMaskElement.h
@@ -37,6 +37,12 @@ class SVGMaskElement final : public SVGElement, public SVGTests {
  public:
   DECLARE_NODE_FACTORY(SVGMaskElement);
 
+  enum {
+    kSvgUnitTypeUnknown = SVGUnitTypes::kSvgUnitTypeUnknown,
+    kSvgUnitTypeUserspaceonuse = SVGUnitTypes::kSvgUnitTypeUserspaceonuse,
+    kSvgUnitTypeObjectboundingbox = SVGUnitTypes::kSvgUnitTypeObjectboundingbox
+  };
+
   SVGAnimatedLength* x() const { return m_x.get(); }
   SVGAnimatedLength* y() const { return m_y.get(); }
   SVGAnimatedLength* width() const { return m_width.get(); }