Add "sample locations" feature to GrProcessor

src/gpu/vk/GrVkGpu.cpp

Index: src/gpu/vk/GrVkGpu.cpp
diff --git a/src/gpu/vk/GrVkGpu.cpp b/src/gpu/vk/GrVkGpu.cpp
index ef2d0be615d0734a3e03f1469d08b9f81219179d..07effa2453eb23b63ca18b8c7d6eae888440195e 100644
--- a/src/gpu/vk/GrVkGpu.cpp
+++ b/src/gpu/vk/GrVkGpu.cpp
@@ -1081,6 +1081,13 @@ bool GrVkGpu::onCopySurface(GrSurface* dst,
     return false;
 }
 
+void GrVkGpu::onGetMultisampleSpecs(GrRenderTarget* rt, const GrStencilSettings&,
+                                    int* effectiveSampleCnt, SkAutoTDeleteArray<SkPoint>*) {
+    // TODO: stub.
+    SkASSERT(!this->caps()->sampleLocationsSupport());
+    *effectiveSampleCnt = rt->desc().fSampleCnt;
+}
+
 bool GrVkGpu::onGetReadPixelsInfo(GrSurface* srcSurface, int width, int height, size_t rowBytes,
                                   GrPixelConfig readConfig, DrawPreference* drawPreference,
                                   ReadPixelTempDrawInfo* tempDrawInfo) {