One signature for creating unit tests that run on premade GrContexts
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1860593002

Review URL: https://codereview.chromium.org/1860593002
diff --git a/tests/GrSurfaceTest.cpp b/tests/GrSurfaceTest.cpp
index ac0b399..280a1c8 100644
--- a/tests/GrSurfaceTest.cpp
+++ b/tests/GrSurfaceTest.cpp
@@ -18,7 +18,8 @@
 
 // Tests that GrSurface::asTexture(), GrSurface::asRenderTarget(), and static upcasting of texture
 // and render targets to GrSurface all work as expected.
-DEF_GPUTEST_FOR_NULL_CONTEXT(GrSurface, reporter, context) {
+DEF_GPUTEST_FOR_NULL_CONTEXT(GrSurface, reporter, ctxInfo) {
+    GrContext* context = ctxInfo.fGrContext;
     GrSurfaceDesc desc;
     desc.fConfig = kSkia8888_GrPixelConfig;
     desc.fFlags = kRenderTarget_GrSurfaceFlag;