added support for glMinSampleShading

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 61fdb8fa33677b22e27279cd4b112c6a9c09d956..c527b5390910ab67df6b2f3c8f20090aa6a7251d 100644
--- a/src/gpu/gl/GrGLGpu.h
+++ b/src/gpu/gl/GrGLGpu.h
@@ -340,6 +340,8 @@ private:
     // rt is used only if useHWAA is true.
     void flushHWAAState(GrRenderTarget* rt, bool useHWAA, bool stencilEnabled);
 
+    void flushMinSampleShading(float minSampleShading);
+
     // helper for onCreateTexture and writeTexturePixels
     enum UploadType {
         kNewTexture_UploadType,    // we are creating a new texture
@@ -619,6 +621,8 @@ private:
     bool fHWPLSEnabled;
     bool fPLSHasBeenUsed;
 
+    float fHWMinSampleShading;
+
     typedef GrGpu INHERITED;
     friend class GrGLPathRendering; // For accessing setTextureUnit.
 };