Add Gr*Proxy classes

src/gpu/GrRenderTarget.cpp

Index: src/gpu/GrRenderTarget.cpp
diff --git a/src/gpu/GrRenderTarget.cpp b/src/gpu/GrRenderTarget.cpp
index a6736403fce612d2f91b2feca254455aef3341e9..ebbfae9b95f07fa722e7617bc2ecaf79cc6b262d 100644
--- a/src/gpu/GrRenderTarget.cpp
+++ b/src/gpu/GrRenderTarget.cpp
@@ -109,3 +109,11 @@ const GrGpu::MultisampleSpecs&
 GrRenderTargetPriv::getMultisampleSpecs(const GrStencilSettings& stencil) const {
     return fRenderTarget->getGpu()->getMultisampleSpecs(fRenderTarget, stencil);
 }
+
+GrRenderTarget::SampleConfig GrRenderTarget::ComputeSampleConfig(const GrCaps& caps,
+                                                                 int sampleCnt) {
+    return (caps.usesMixedSamples() && sampleCnt > 0)
+                        ? GrRenderTarget::kStencil_SampleConfig
+                        : GrRenderTarget::kUnified_SampleConfig;
+}
+