Add "sample locations" feature to GrProcessor

include/gpu/GrRenderTarget.h

Index: include/gpu/GrRenderTarget.h
diff --git a/include/gpu/GrRenderTarget.h b/include/gpu/GrRenderTarget.h
index d39d284bd8259a90a8b43b93f1ca28ca65e13f7d..007c42a8d4a15ef189d5e138c05670e687b364a0 100644
--- a/include/gpu/GrRenderTarget.h
+++ b/include/gpu/GrRenderTarget.h
@@ -193,6 +193,30 @@ private:
     // and the drawTarget of a destination renderTarget to which this one is being drawn.
     GrDrawTarget* fLastDrawTarget;
 
+    /**
+     * Info struct filled out by GrGpu that contains hardware-specific multisample info.
+     */
+    struct MultisampleSpecs {
+        MultisampleSpecs() { memset(this, 0, sizeof(*this)); }
+        /**
+         * The actual number of samples allocated for the render target. NOTE: this value can be
+         * greater than the surface descriptor's sample count.
+         */
+        int             fEffectiveSampleCnt;
+        /**
+         * If sample locations are supported, contains a unique ID that identifies the render
+         * target's sample pattern. Otherwise 0.
+         */
+        uint16_t        fSamplePatternID;
+        /**
+         * If supported, references the render target's sample locations. Otherwise nullptr. The
+         * sample locations are stored in device space, with the center of the pixel at [0.5, 0.5].
+         */
+        const SkPoint*  fSampleLocations;
+    };
+
+    SkAutoTDelete<MultisampleSpecs> fMultisampleSpecs;
+
     typedef GrSurface INHERITED;
 };