SkShaper: optionally disable harfbuzz

tools/SkShaper.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 SkShaper_DEFINED
 #define SkShaper_DEFINED
 
 #include <memory>
 
 #include "SkPoint.h"
 #include "SkTypeface.h"
 
 class SkPaint;
 class SkTextBlobBuilder;
 
 /**
-   Shapes text using harfbuzz and places the shaped text into a
+   Shapes text using HarfBuzz and places the shaped text into a
    TextBlob.
+
+   If compiled without HarfBuzz, fall back on SkPaint::textToGlyphs.
  */
 class SkShaper {
 public:
     SkShaper(sk_sp<SkTypeface> face);
     ~SkShaper();
 
     bool good() const;
     SkScalar shape(SkTextBlobBuilder* dest,
                    const SkPaint& srcPaint,
                    const char* utf8text,
                    size_t textBytes,
                    SkPoint point) const;
 
 private:
     SkShaper(const SkShaper&) = delete;
     SkShaper& operator=(const SkShaper&) = delete;
 
     struct Impl;
     std::unique_ptr<Impl> fImpl;
 };
 
 #endif  // SkShaper_DEFINED