[SVGDom] Add <svg> viewBox support

experimental/svg/model/SkSVGAttributeParser.h

 /*
  * 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 SkSVGAttributeParser_DEFINED
 #define SkSVGAttributeParser_DEFINED
 
 #include "SkSVGTypes.h"
 
 class SkSVGAttributeParser : public SkNoncopyable {
 public:
     SkSVGAttributeParser(const char[]);
 
-    bool parseColor(SkSVGColor*);
-    bool parseNumber(SkSVGNumber*);
+    bool parseColor(SkSVGColorType*);
+    bool parseNumber(SkSVGNumberType*);
     bool parseLength(SkSVGLength*);
+    bool parseViewBox(SkSVGViewBoxType*);
 
 private:
     // Stack-only
     void* operator new(size_t) = delete;
     void* operator new(size_t, void*) = delete;
 
     template <typename F>
     bool advanceWhile(F func);
 
     bool parseWSToken();
     bool parseEOSToken();
     bool parseSepToken();
     bool parseExpectedStringToken(const char*);
     bool parseScalarToken(SkScalar*);
     bool parseHexToken(uint32_t*);
     bool parseLengthUnitToken(SkSVGLength::Unit*);
     bool parseNamedColorToken(SkColor*);
     bool parseHexColorToken(SkColor*);
 
     // The current position in the input string.
     const char* fCurPos;
 
     typedef SkNoncopyable INHERITED;
 };
 
 #endif // SkSVGAttributeParser_DEFINED