[SVGDom] Add support for assorted absolute units

experimental/svg/model/SkSVGRenderContext.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 SkSVGRenderContext_DEFINED
 #define SkSVGRenderContext_DEFINED
 
 #include "SkPaint.h"
 #include "SkRect.h"
 #include "SkSize.h"
 #include "SkSVGAttribute.h"
 #include "SkTLazy.h"
 #include "SkTypes.h"
 
 class SkCanvas;
 class SkSVGLength;
 
 class SkSVGLengthContext {
 public:
-    SkSVGLengthContext(const SkSize& viewport) : fViewport(viewport) {}
+    SkSVGLengthContext(const SkSize& viewport, SkScalar dpi = 90)
+        : fViewport(viewport), fDPI(dpi) {}
 
     enum class LengthType {
         kHorizontal,
         kVertical,
         kOther,
     };
 
     const SkSize& viewPort() const { return fViewport; }
     void setViewPort(const SkSize& viewport) { fViewport = viewport; }
 
     SkScalar resolve(const SkSVGLength&, LengthType) const;
     SkRect   resolveRect(const SkSVGLength& x, const SkSVGLength& y,
                          const SkSVGLength& w, const SkSVGLength& h) const;
 
 private:
-    SkSize fViewport;
+    SkSize   fViewport;
+    SkScalar fDPI;
 };
 
 struct SkSVGPresentationContext {
     SkSVGPresentationContext();
     SkSVGPresentationContext(const SkSVGPresentationContext&)            = default;
     SkSVGPresentationContext& operator=(const SkSVGPresentationContext&) = default;
 
     // Inherited presentation attributes, computed for the current node.
     SkSVGPresentationAttributes fInherited;
 
@@ skipping 26 matching lines @@
 
     SkTCopyOnFirstWrite<SkSVGLengthContext>       fLengthContext;
     SkTCopyOnFirstWrite<SkSVGPresentationContext> fPresentationContext;
     SkCanvas*                                     fCanvas;
     // The save count on 'fCanvas' at construction time.
     // A restoreToCount() will be issued on destruction.
     int                                           fCanvasSaveCount;
 };
 
 #endif // SkSVGRenderContext_DEFINED