Add "sample locations" feature to GrProcessor

src/gpu/vk/GrVkGpu.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 GrVkGpu_DEFINED
 #define GrVkGpu_DEFINED
 
@@ skipping 58 matching lines @@
 
     void discard(GrRenderTarget*) override {
         SkDebugf("discard not yet implemented for Vulkan\n");
     }
 
     bool onCopySurface(GrSurface* dst,
                        GrSurface* src,
                        const SkIRect& srcRect,
                        const SkIPoint& dstPoint) override;
 
+    void onGetMultisampleSpecs(GrRenderTarget* rt,
+                               const GrStencilSettings&,
+                               int* effectiveSampleCnt,
+                               SkAutoTDeleteArray<SkPoint>*);
+
     bool initCopySurfaceDstDesc(const GrSurface* src, GrSurfaceDesc* desc) const override {
         SkDebugf("initCopySurfaceDstDesc not yet implemented for Vulkan\n");
         return false;
     }
 
     void xferBarrier(GrRenderTarget*, GrXferBarrierType) override {}
 
     GrBackendObject createTestingOnlyBackendTexture(void* pixels, int w, int h,
                                                     GrPixelConfig config) override;
     bool isTestingOnlyBackendTexture(GrBackendObject id) const override;
@@ skipping 127 matching lines @@
     shaderc_compiler_t fCompiler;
 
     // This is only for our current testing and building. The client should be holding on to the
     // VkInstance.
     VkInstance                        fVkInstance;
 
     typedef GrGpu INHERITED;
 };
 
 #endif