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

src/gpu/GrGpu.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 GrGpu_DEFINED
 #define GrGpu_DEFINED
 
@@ skipping 355 matching lines @@
 
     Stats* stats() { return &fStats; }
 
     // creation and deletion of raw texture for testing
     // only to be used in GPU-specific tests
     virtual GrBackendObject createTestingOnlyBackendTexture(void* pixels, int w, int h,
                                                             GrPixelConfig config) const = 0;
     virtual bool isTestingOnlyBackendTexture(GrBackendObject id) const = 0;
     virtual void deleteTestingOnlyBackendTexture(GrBackendObject id) const = 0;
 
-    // Given a rt, find or create a stencil buffer and attach it
-    bool attachStencilAttachmentToRenderTarget(GrRenderTarget* target);
+    // Given the input GrRenderTarget, this function sets GrStencilAttachment* either
+    // from a cached stencil attachment or by creating a new one. If the GrStencilAttachment*
+    // that is returned is non-null, the caller will own the ref on the GrStencilAttachment.
+    // This function returns true if the returned GrStencilAttachment was newly created in case
+    // the caller wants to do any special thing with the stencil (e.g. clearning it).
+    bool getStencilAttachment(const GrRenderTarget*, GrStencilAttachment**);
+
+    // clears target's entire stencil buffer to 0
+    virtual void clearStencil(GrRenderTarget* target) = 0;
 
     // This is only to be used in GL-specific tests.
     virtual const GrGLContext* glContextForTesting() const { return nullptr; }
 
 protected:
     // Functions used to map clip-respecting stencil tests into normal
     // stencil funcs supported by GPUs.
     static GrStencilFunc ConvertStencilFunc(bool stencilInClip,
                                             GrStencilFunc func);
     static void ConvertStencilFuncAndMask(GrStencilFunc func,
@@ skipping 76 matching lines @@
     // overridden by backend-specific derived class to perform the resolve
     virtual void onResolveRenderTarget(GrRenderTarget* target) = 0;
 
     // overridden by backend specific derived class to perform the copy surface
     virtual bool onCopySurface(GrSurface* dst,
                                GrSurface* src,
                                const SkIRect& srcRect,
                                const SkIPoint& dstPoint) = 0;
 
     // width and height may be larger than rt (if underlying API allows it).
-    // Should attach the SB to the RT. Returns false if compatible sb could
-    // not be created.
-    virtual bool createStencilAttachmentForRenderTarget(GrRenderTarget*, int width, int height) = 0;
-
-    // attaches an existing SB to an existing RT.
-    virtual bool attachStencilAttachmentToRenderTarget(GrStencilAttachment*, GrRenderTarget*) = 0;
-
-    // clears target's entire stencil buffer to 0
-    virtual void clearStencil(GrRenderTarget* target) = 0;
+    // Returns nullptr if compatible sb could not be created.
+    virtual GrStencilAttachment* createStencilAttachmentForRenderTarget(const GrRenderTarget*,
+                                                                        int width,
+                                                                        int height) = 0;
 
     void resetContext() {
         this->onResetContext(fResetBits);
         fResetBits = 0;
         ++fResetTimestamp;
     }
 
     void handleDirtyContext() {
         if (fResetBits) {
             this->resetContext();
         }
     }
 
     ResetTimestamp                                                      fResetTimestamp;
     uint32_t                                                            fResetBits;
     // The context owns us, not vice-versa, so this ptr is not ref'ed by Gpu.
     GrContext*                                                          fContext;
 
     friend class GrPathRendering;
     typedef SkRefCnt INHERITED;
 };
 
 #endif