Revert of Broke GrTessellatingPathRenderer's tessellator out into a separate file.

src/gpu/GrTessellator.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 GrTessellator_DEFINED
-#define GrTessellator_DEFINED
-
-#include "SkPath.h"
-#include "GrResourceProvider.h"
-
-/**
- * Provides utility functions for converting paths to a collection of triangles.
- */
-
-#define TESSELLATOR_WIREFRAME 0
-
-namespace GrTessellator {
-
-struct WindingVertex {
-    SkPoint fPos;
-    int fWinding;
-};
-
-// Triangulates a path to an array of vertices. Each triangle is represented as a set of three
-// WindingVertex entries, each of which contains the position and winding count (which is the same
-// for all three vertices of a triangle). The 'verts' out parameter is set to point to the resultant
-// vertex array. CALLER IS RESPONSIBLE for deleting this buffer to avoid a memory leak!
-int PathToVertices(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 
-                   WindingVertex** verts);
-
-int PathToTriangles(const SkPath& path, SkScalar tolerance, const SkRect& clipBounds, 
-                    GrResourceProvider* resourceProvider, 
-                    SkAutoTUnref<GrVertexBuffer>& vertexBuffer, bool canMapVB, bool* isLinear);
-
-}
-
-#endif