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

include/gpu/GrRenderTarget.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrRenderTarget_DEFINED
 #define GrRenderTarget_DEFINED
 
@@ skipping 126 matching lines @@
         kCantResolve_ResolveType,
     };
     virtual ResolveType getResolveType() const = 0;
 
     /**
      *  Return the native ID or handle to the rendertarget, depending on the
      *  platform. e.g. on OpenGL, return the FBO ID.
      */
     virtual GrBackendObject getRenderTargetHandle() const = 0;
 
+    // Checked when this object is asked to attach a stencil buffer.
+    virtual bool canAttemptStencilAttachment() const = 0;
+
     // Provides access to functions that aren't part of the public API.
     GrRenderTargetPriv renderTargetPriv();
     const GrRenderTargetPriv renderTargetPriv() const;
 
 protected:
     GrRenderTarget(GrGpu* gpu, LifeCycle lifeCycle, const GrSurfaceDesc& desc,
-                   SampleConfig sampleConfig)
+                   SampleConfig sampleConfig, GrStencilAttachment* stencil = nullptr)
         : INHERITED(gpu, lifeCycle, desc)
-        , fStencilAttachment(NULL)
+        , fStencilAttachment(stencil)
         , fSampleConfig(sampleConfig) {
         fResolveRect.setLargestInverted();
     }
 
     // override of GrResource
     void onAbandon() override;
     void onRelease() override;
 
 private:
-    // Checked when this object is asked to attach a stencil buffer.
-    virtual bool canAttemptStencilAttachment() const = 0;
+    // Allows the backends to perform any additional work that is required for attaching a
+    // GrStencilAttachment. When this is called, the GrStencilAttachment has already been put onto
+    // the GrRenderTarget. This function must return false if any failures occur when completing the
+    // stencil attachment.
+    virtual bool completeStencilAttachment() = 0;
 
     friend class GrRenderTargetPriv;
 
     GrStencilAttachment*  fStencilAttachment;
     SampleConfig          fSampleConfig;
 
     SkIRect               fResolveRect;
 
     typedef GrSurface INHERITED;
 };
 
 
 #endif