Move GrTextContext to private interface

include/gpu/GrDistanceFieldTextContext.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 GrDistanceFieldTextContext_DEFINED
-#define GrDistanceFieldTextContext_DEFINED
-
-#include "GrTextContext.h"
-
-class GrTextStrike;
-
-/*
- * This class implements GrTextContext using distance field fonts
- */
-class GrDistanceFieldTextContext : public GrTextContext {
-public:
-    virtual void drawText(const char text[], size_t byteLength, SkScalar x, SkScalar y) SK_OVERRIDE;
-    virtual void drawPosText(const char text[], size_t byteLength,
-                             const SkScalar pos[], SkScalar constY,
-                             int scalarsPerPosition) SK_OVERRIDE;
-    
-    static bool CanDraw(const SkPaint& paint, const SkMatrix& ctm);
-
-private:
-    GrDistanceFieldTextContext(GrContext*, const GrPaint&, const SkPaint&,
-                               const SkDeviceProperties&);
-    virtual ~GrDistanceFieldTextContext();
-    friend class GrTTextContextManager<GrDistanceFieldTextContext>;
-
-    GrTextStrike*           fStrike;
-    SkScalar                fTextRatio;
-
-    void drawPackedGlyph(GrGlyph::PackedID, GrFixed left, GrFixed top, GrFontScaler*);
-    void flushGlyphs();                 // automatically called by destructor
-
-    enum {
-        kMinRequestedGlyphs      = 1,
-        kDefaultRequestedGlyphs  = 64,
-        kMinRequestedVerts       = kMinRequestedGlyphs * 4,
-        kDefaultRequestedVerts   = kDefaultRequestedGlyphs * 4,
-    };
-
-    SkPoint*                fVertices;
-    int32_t                 fMaxVertices;
-    GrTexture*              fCurrTexture;
-    int                     fCurrVertex;
-};
-
-#endif