Change GrTextContext fallbacks to be a linked list chain.

src/gpu/GrDistanceFieldTextContext.h

Index: src/gpu/GrDistanceFieldTextContext.h
diff --git a/src/gpu/GrDistanceFieldTextContext.h b/src/gpu/GrDistanceFieldTextContext.h
index d628e3e3bdd81673556457a32ef63dac2d67f495..6fa2d6f173855b0debde9650bcc6259dea9fac5b 100644
--- a/src/gpu/GrDistanceFieldTextContext.h
+++ b/src/gpu/GrDistanceFieldTextContext.h
@@ -18,17 +18,9 @@ class GrTextStrike;
  */
 class GrDistanceFieldTextContext : public GrTextContext {
 public:
-    GrDistanceFieldTextContext(GrContext*, const SkDeviceProperties&, bool enable);
-    virtual ~GrDistanceFieldTextContext();
+    static GrDistanceFieldTextContext* Create(GrContext*, const SkDeviceProperties&, bool enable);
 
-    virtual bool canDraw(const SkPaint& paint) SK_OVERRIDE;
-
-    virtual void drawText(const GrPaint&, const SkPaint&, const char text[], size_t byteLength,
-                          SkScalar x, SkScalar y) SK_OVERRIDE;
-    virtual void drawPosText(const GrPaint&, const SkPaint&,
-                             const char text[], size_t byteLength,
-                             const SkScalar pos[], int scalarsPerPosition,
-                             const SkPoint& offset) SK_OVERRIDE;
+    virtual ~GrDistanceFieldTextContext();
 
 private:
     enum {
@@ -54,6 +46,17 @@ private:
     int                                fCurrVertex;
     SkRect                             fVertexBounds;
 
+    GrDistanceFieldTextContext(GrContext*, const SkDeviceProperties&, bool enable);
+
+    virtual bool canDraw(const SkPaint& paint) SK_OVERRIDE;
+
+    virtual void onDrawText(const GrPaint&, const SkPaint&, const char text[], size_t byteLength,
+                            SkScalar x, SkScalar y) SK_OVERRIDE;
+    virtual void onDrawPosText(const GrPaint&, const SkPaint&,
+                               const char text[], size_t byteLength,
+                               const SkScalar pos[], int scalarsPerPosition,
+                               const SkPoint& offset) SK_OVERRIDE;
+
     void init(const GrPaint&, const SkPaint&);
     void appendGlyph(GrGlyph::PackedID, SkFixed left, SkFixed top, GrFontScaler*);
     void setupCoverageEffect(const SkColor& filteredColor);