Enable stencil clipping in mixed sampled render targets

src/gpu/gl/GrGLGpu.h

Index: src/gpu/gl/GrGLGpu.h
diff --git a/src/gpu/gl/GrGLGpu.h b/src/gpu/gl/GrGLGpu.h
index 833f1ff7ec0356adeae9e6ffe1e7f9fd8a7b5f59..4a86f62b22b5b16470bdd07084fb1cc3a6eecaf8 100644
--- a/src/gpu/gl/GrGLGpu.h
+++ b/src/gpu/gl/GrGLGpu.h
@@ -256,6 +256,10 @@ private:
     // ensures that such operations don't negatively interact with tracking bound textures.
     void setScratchTextureUnit();
 
+    // enables or disables programmable sample locations for render target, if MSAA.
+    // allows overriding default sample locations used by hardware.
+    void setProgrammableSampleLocations(GrRenderTarget* rt, bool useSampleLocations);

[Chris Dalton, 2015/09/22 08:35:24]

I wonder if this should have a different name, since its actual purpose seems to
be enabling centered, co-located sample positions?

Either that, or this method accepts an array of sample positions and the caller
supplies centered locdations (or whatever it wants).

+
     // bounds is region that may be modified and therefore has to be resolved.
     // nullptr means whole target. Can be an empty rect.
     void flushRenderTarget(GrGLRenderTarget*, const SkIRect* bounds);