Move all text stuff to its own folder

src/gpu/GrDistanceFieldAdjustTable.h

-/*
- * Copyright 2015 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#ifndef GrDistanceFieldAdjustTable_DEFINED
-#define GrDistanceFieldAdjustTable_DEFINED
-
-#include "SkRefCnt.h"
-#include "SkScalar.h"
-
-// Distance field text needs this table to compute a value for use in the fragment shader.
-// Because the GrAtlasTextContext can go out of scope before the final flush, this needs to be
-// refcnted and malloced
-struct GrDistanceFieldAdjustTable : public SkNVRefCnt<GrDistanceFieldAdjustTable> {
-    GrDistanceFieldAdjustTable() { this->buildDistanceAdjustTable(); }
-    ~GrDistanceFieldAdjustTable() { delete[] fTable; }
-
-    const SkScalar& operator[] (int i) const {
-        return fTable[i];
-    }
-
-private:
-    void buildDistanceAdjustTable();
-
-    SkScalar* fTable;
-};
-
-#endif