Implement support for mixed sampled render targets

src/gpu/gl/GrGLRenderTarget.h

Index: src/gpu/gl/GrGLRenderTarget.h
diff --git a/src/gpu/gl/GrGLRenderTarget.h b/src/gpu/gl/GrGLRenderTarget.h
index 485ae4a7919d1d967b8600ac8c8093da80fe4af1..80d0bb0dae2ae158f3457918bfa80eeb467aa180 100644
--- a/src/gpu/gl/GrGLRenderTarget.h
+++ b/src/gpu/gl/GrGLRenderTarget.h
@@ -70,6 +70,7 @@ public:
         SkAutoTUnref<GrGLFBO>       fTextureFBO;
         GrGLuint                    fMSColorRenderbufferID;
         GrGpuResource::LifeCycle    fLifeCycle;
+        GrSampleConfig              fSampleConfig;
     };
 
     GrGLRenderTarget(GrGLGpu*, const GrSurfaceDesc&, const IDDesc&);