ui/gfx: Make gfx::Canvas inherit from gfx::CanvasSkia.

ui/gfx/canvas_skia.cc

Index: ui/gfx/canvas_skia.cc
diff --git a/ui/gfx/canvas_skia.cc b/ui/gfx/canvas_skia.cc
index 5ae821c1c9b9dd662fa71be2a86f232f141cc89a..fe03bc01974713df222de300abfe7b605e5aa21f 100644
--- a/ui/gfx/canvas_skia.cc
+++ b/ui/gfx/canvas_skia.cc
@@ -363,14 +363,6 @@ void CanvasSkia::Transform(const ui::Transform& transform) {
   canvas_->concat(transform.matrix());
 }
 
-CanvasSkia* CanvasSkia::AsCanvasSkia() {
-  return this;
-}
-
-const CanvasSkia* CanvasSkia::AsCanvasSkia() const {
-  return this;
-}
-
 SkCanvas* CanvasSkia::GetSkCanvas() {
   return canvas_;
 }
@@ -389,15 +381,4 @@ bool CanvasSkia::IntersectsClipRectInt(int x, int y, int w, int h) {
                      SkIntToScalar(y + h));
 }
 
-////////////////////////////////////////////////////////////////////////////////
-// Canvas, public:
-
-Canvas* Canvas::CreateCanvas() {
-  return new CanvasSkia;
-}
-
-Canvas* Canvas::CreateCanvas(const gfx::Size& size, bool is_opaque) {
-  return new CanvasSkia(size, is_opaque);
-}
-
 }  // namespace gfx