Add "sample locations" feature to GrProcessor

src/gpu/GrRenderTargetPriv.h

Index: src/gpu/GrRenderTargetPriv.h
diff --git a/src/gpu/GrRenderTargetPriv.h b/src/gpu/GrRenderTargetPriv.h
index f4931db1db7475feab36d24f163aeec8b4bc0f7e..2d2fe94a294732c3b5b20a83594a3c2e0b2bca24 100644
--- a/src/gpu/GrRenderTargetPriv.h
+++ b/src/gpu/GrRenderTargetPriv.h
@@ -10,11 +10,15 @@
 
 #include "GrRenderTarget.h"
 
+class GrStencilSettings;
+
 /** Class that adds methods to GrRenderTarget that are only intended for use internal to Skia.
     This class is purely a privileged window into GrRenderTarget. It should never have additional
     data members or virtual methods. */
 class GrRenderTargetPriv {
 public:
+    typedef GrRenderTarget::MultisampleSpecs MultisampleSpecs;
+
     /**
      * GrStencilAttachment is not part of the public API.
      */
@@ -27,6 +31,37 @@ public:
      */
     bool attachStencilAttachment(GrStencilAttachment* stencil);
 
+    /**
+     * Returns the actual number of samples the GPU will run when drawing to this render target with
+     * HW antialiasing and the provided stencil settings. NOTE: this can be greater than the sample
+     * count in the render target's surface descriptor.
+     */
+    int getEffectiveSampleCount(const GrStencilSettings&) const;
+
+    /**
+     * Returns a nonzero unique ID that identifies the sample pattern the GPU will use when drawing
+     * to this render target with HW antialiasing and the provided stencil settings.
+     *
+     * Requires support for sample locations.
+     */
+    uint16_t getSamplePatternID(const GrStencilSettings&) const;
+
+    /**
+     * Returns the sample locations the GPU will use when drawing to this render target with HW
+     * antialiasing and the provided stencil settings. The sample locations are stored in device
+     * space, with the center of the pixel at [0.5, 0.5].
+     *
+     * Requires support for sample locations.
+     */
+    const SkPoint* getSampleLocations(const GrStencilSettings&) const;
+
+    /**
+     * Used by GrGpu to cache the render target's multisample info.
+     */
+    SkAutoTDelete<MultisampleSpecs>* accessMultisampleSpecs() {
+        return &fRenderTarget->fMultisampleSpecs;
+    }
+
 private:
     explicit GrRenderTargetPriv(GrRenderTarget* renderTarget) : fRenderTarget(renderTarget) {}
     GrRenderTargetPriv(const GrRenderTargetPriv&) {} // unimpl