Add effect caching to distance field text.

src/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
 
@@ skipping 16 matching lines @@
                              const SkScalar pos[], SkScalar constY,
                              int scalarsPerPosition) SK_OVERRIDE;
 
     virtual bool canDraw(const SkPaint& paint) SK_OVERRIDE;
 
 private:
     GrTextStrike*           fStrike;
     SkScalar                fTextRatio;
     bool                    fUseLCDText;
     bool                    fEnableDFRendering;
+    SkAutoTUnref<GrEffect>  fCachedEffect;
+    // Used to check whether fCachedEffect is still valid.
+    uint32_t                fEffectTextureUniqueID;
+    SkColor                 fEffectColor;
+    uint32_t                fEffectFlags;
     GrTexture*              fGammaTexture;
 
     void init(const GrPaint&, const SkPaint&);
     void drawPackedGlyph(GrGlyph::PackedID, SkFixed left, SkFixed top, GrFontScaler*);
     void flushGlyphs();                 // automatically called by destructor
+    void setupCoverageEffect(const SkColor& filteredColor);
     void finish();
 
     enum {
         kMinRequestedGlyphs      = 1,
         kDefaultRequestedGlyphs  = 64,
         kMinRequestedVerts       = kMinRequestedGlyphs * 4,
         kDefaultRequestedVerts   = kDefaultRequestedGlyphs * 4,
     };
 
     void*                   fVertices;
     int                     fCurrVertex;
 };
 
 #endif