Move some of the adding stencil attachment logic of Gpu and into Render Target.

src/gpu/GrResourceProvider.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 GrResourceProvider_DEFINED
 #define GrResourceProvider_DEFINED
 
 #include "GrBatchAtlas.h"
 #include "GrIndexBuffer.h"
 #include "GrTextureProvider.h"
 #include "GrPathRange.h"
 
 class GrBatchAtlas;
 class GrIndexBuffer;
 class GrPath;
+class GrRenderTarget;
+class GrStencilAttachment;
 class GrStrokeInfo;
 class GrVertexBuffer;
 class SkDescriptor;
 class SkPath;
 class SkTypeface;
 
 /**
  * An extension of the texture provider for arbitrary resource types. This class is intended for
  * use within the Gr code base, not by clients or extensions (e.g. third party GrProcessor
  * derivatives).
@@ skipping 98 matching lines @@
      *   @param func             An eviction function which will be called whenever the atlas has to
      *                           evict data
      *   @param data             User supplied data which will be passed into func whenver an
      *                           eviction occurs
      *
      *   @return                 An initialized GrBatchAtlas, or nullptr if creation fails
      */
     GrBatchAtlas* createAtlas(GrPixelConfig, int width, int height, int numPlotsX, int numPlotsY,
                               GrBatchAtlas::EvictionFunc func, void* data);
 
+    /**
+     * If passed in render target already has a stencil buffer, return it. Otherwise attempt to
+     * attach one.
+     */
+    GrStencilAttachment* attachStencilAttachment(GrRenderTarget* rt);
+
 private:
     const GrIndexBuffer* createInstancedIndexBuffer(const uint16_t* pattern,
                                                     int patternSize,
                                                     int reps,
                                                     int vertCount,
                                                     const GrUniqueKey& key);
 
     const GrIndexBuffer* createQuadIndexBuffer();
 
     GrUniqueKey fQuadIndexBufferKey;
 
     typedef GrTextureProvider INHERITED;
 };
 
 #endif