Start canonicalizing color for all A8 textblobs

include/core/SkPaint.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPaint_DEFINED
 #define SkPaint_DEFINED
 
@@ skipping 1058 matching lines @@
     void getScalerContextDescriptor(SkAutoDescriptor*, const SkDeviceProperties* deviceProperties,
                                     const SkMatrix*, bool ignoreGamma) const;
 
     SkGlyphCache* detachCache(const SkDeviceProperties* deviceProperties, const SkMatrix*,
                               bool ignoreGamma) const;
 
     void descriptorProc(const SkDeviceProperties* deviceProperties, const SkMatrix* deviceMatrix,
                         void (*proc)(SkTypeface*, const SkDescriptor*, void*),
                         void* context, bool ignoreGamma = false) const;
 
+    SkColor computeLuminanceColor() const;

[bsalomon, 2015/04/13 15:16:38]

comment about what luminance color is? Or is this something that already has a
clear meaning in Skia?

+
     static void Term();
 
     enum {
         /*  This is the size we use when we ask for a glyph's path. We then
          *  post-transform it as we draw to match the request.
          *  This is done to try to re-use cache entries for the path.
          *
          *  This value is somewhat arbitrary. In theory, it could be 1, since
          *  we store paths as floats. However, we get the path from the font
          *  scaler, and it may represent its paths as fixed-point (or 26.6),
@@ skipping 33 matching lines @@
     friend class SkDraw;
     friend class SkGraphics; // So Term() can be called.
     friend class SkPDFDevice;
     friend class GrBitmapTextContext;
     friend class GrAtlasTextContext;
     friend class GrDistanceFieldTextContext;
     friend class GrStencilAndCoverTextContext;
     friend class GrPathRendering;
     friend class GrTextContext;
     friend class GrGLPathRendering;
+    friend class SkScalerContext;
     friend class SkTextToPathIter;
     friend class SkCanonicalizePaint;
 };
 
 #endif