Return GrGLContext from GrTestTarget

tests/SurfaceTest.cpp

Index: tests/SurfaceTest.cpp
diff --git a/tests/SurfaceTest.cpp b/tests/SurfaceTest.cpp
index cfaa6692628d3478c1effd453894ca9baf263e44..c45e94e883cd3fd9402e35029bd1cd1775aca39b 100644
--- a/tests/SurfaceTest.cpp
+++ b/tests/SurfaceTest.cpp
@@ -115,7 +115,7 @@ static void test_wrapped_texture_surface(skiatest::Reporter* reporter, GrContext
     }
 
     // We currently have only implemented the texture uploads for GL.
-    const GrGLInterface* gl = tt.glInterface();
+    const GrGLInterface* gl = tt.glContext()->interface();
     if (!gl) {
         return;
     }