Add "sample locations" feature to GrProcessor

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 347 matching lines @@
 
     // Called to perform a surface to surface copy. Fallbacks to issuing a draw from the src to dst
     // take place at the GrDrawTarget level and this function implement faster copy paths. The rect
     // and point are pre-clipped. The src rect and implied dst rect are guaranteed to be within the
     // src/dst bounds and non-empty.
     bool copySurface(GrSurface* dst,
                      GrSurface* src,
                      const SkIRect& srcRect,
                      const SkIPoint& dstPoint);
 
+    const GrCaps::MultisampleSpecs& getMultisampleSpecs(GrRenderTarget* rt,
+                                                        const GrStencilSettings& stencil) {
+        using namespace std::placeholders;
+        const auto& functor = std::bind(&GrGpu::onGetMultisampleSpecs, this, rt, stencil, _1, _2);
+        return this->caps()->getMultisampleSpecs(rt->desc(), functor);
+    }
+
     struct DrawArgs {
         DrawArgs(const GrPrimitiveProcessor* primProc,
                  const GrPipeline* pipeline,
                  const GrProgramDesc* desc)
             : fPrimitiveProcessor(primProc)
             , fPipeline(pipeline)
             , fDesc(desc) {
             SkASSERT(primProc && pipeline && desc);
         }
         const GrPrimitiveProcessor* fPrimitiveProcessor;
@@ skipping 216 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;
 
+    // overridden by backend specific derived class to perform the multisample queries
+    virtual void onGetMultisampleSpecs(GrRenderTarget*,
+                                       const GrStencilSettings&,
+                                       int* effectiveSampleCnt,
+                                       SkAutoTDeleteArray<SkPoint>* samplePattern) = 0;
+
     void resetContext() {
         this->onResetContext(fResetBits);
         fResetBits = 0;
         ++fResetTimestamp;
     }
 
     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