Remove the SkCanvas comment API

experimental/PdfViewer/SkNulCanvas.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkNulCanvas_DEFINED
 #define SkNulCanvas_DEFINED
 
 #include "SkCanvas.h"
 
 /** \class SkNulCanvas
  *
  *   Nul Canvas is a canvas that does nothing. It is used to measure the perf of just parsing
  *   a pdf, without actually rendering anything.
  *
  */
 class SK_API SkNulCanvas : public SkCanvas {
 public:
     SK_DECLARE_INST_COUNT(SkNulCanvas);
 
     SkNulCanvas() {}
     explicit SkNulCanvas(SkBaseDevice* device) : SkCanvas(device) {}
 
     explicit SkNulCanvas(const SkBitmap& bitmap) : SkCanvas(bitmap) {}
     virtual ~SkNulCanvas() {}
 
-    void beginCommentGroup(const char* description) override {}
-    void addComment(const char* kywd, const char* value) override {}
-    void endCommentGroup() override {}
     SkDrawFilter* setDrawFilter(SkDrawFilter* filter) override {return NULL;}
 
     bool isClipEmpty() const override { return false; }
     bool getClipBounds(SkRect* bounds) const override {
         if (NULL != bounds) {
             bounds->setXYWH(0, 0,
                             SkIntToScalar(this->imageInfo().width()),
                             SkIntToScalar(this->imageInfo().height()));
         }
         return true;
@@ skipping 58 matching lines @@
                         const SkColor colors[], SkXfermode* xmode,
                         const uint16_t indices[], int indexCount,
                         const SkPaint& paint) override {}
 
     
 private:
     typedef SkCanvas INHERITED;
 };
 
 #endif  // SkNulCanvas_DEFINED